feat: Phase 6 — Living Taxonomy + Universal Capture

Closes two real-use gaps:
1. "APM tool" gap: work done outside Claude Code (desktop, web, phone,
   other machine) was invisible to AtoCore.
2. Project discovery gap: manual JSON-file edits required to promote
   an emerging theme to a first-class project.

B — atocore_remember MCP tool (scripts/atocore_mcp.py):
- New MCP tool for universal capture from any MCP-aware client
  (Claude Desktop, Code, Cursor, Zed, Windsurf, etc.)
- Accepts content (required) + memory_type/project/confidence/
  valid_until/domain_tags (all optional with sensible defaults)
- Creates a candidate memory, goes through the existing 3-tier triage
  (no bypass — the quality gate catches noise)
- Detailed tool description guides Claude on when to invoke: "remember
  this", "save that for later", "don't lose this fact"
- Total tools exposed by MCP server: 14 → 15

C.1 Emerging-concepts detector (scripts/detect_emerging.py):
- Nightly scan of active + candidate memories for:
  * Unregistered project names with ≥3 memory occurrences
  * Top 20 domain_tags by frequency (emerging categories)
  * Active memories with reference_count ≥ 5 + valid_until set
    (reinforced transients — candidates for extension)
- Writes findings to atocore/proposals/* project state entries
- Emits "warning" alert via Phase 4 framework the FIRST time a new
  project crosses the 5-memory alert threshold (avoids spam)
- Configurable via env vars: ATOCORE_EMERGING_PROJECT_MIN (default 3),
  ATOCORE_EMERGING_ALERT_THRESHOLD (default 5), TOP_TAGS_LIMIT (20)

C.2 Registration surface (src/atocore/api/routes.py + wiki.py):
- POST /admin/projects/register-emerging — one-click register with
  sensible defaults (ingest_roots auto-filled with
  vault:incoming/projects/<id>/ convention). Clears the proposal
  from the dashboard list on success.
- Dashboard /admin/dashboard: new "proposals" section with
  unregistered_projects + emerging_categories + reinforced_transients.
- Wiki homepage: "📋 Emerging" section rendering each unregistered
  project as a card with count + 2 sample memory previews + inline
  "📌 Register as project" button that calls the endpoint via fetch,
  reloads the page on success.

C.3 Transient-to-durable extension
(src/atocore/memory/service.py + API + cron):
- New extend_reinforced_valid_until() function — scans active memories
  with valid_until in the next 30 days and reference_count ≥ 5.
  Extends expiry by 90 days. If reference_count ≥ 10, clears expiry
  entirely (makes permanent). Writes audit rows via the Phase 4
  memory_audit framework with actor="transient-to-durable".
- POST /admin/memory/extend-reinforced — API wrapper for cron.
- Matches the user's intuition: "something transient becomes important
  if you keep coming back to it".

Nightly cron (deploy/dalidou/batch-extract.sh):
- Step F2: detect_emerging.py (after F pipeline summary)
- Step F3: /admin/memory/extend-reinforced (before integrity check)
- Both fail-open; errors don't break the pipeline.

Tests: 366 → 374 (+8 for Phase 6):
- 6 tests for extend_reinforced_valid_until covering:
  extension path, permanent path, skip far-future, skip low-refs,
  skip permanent memories, audit row write
- 2 smoke tests for the detector (imports cleanly, handles empty DB)
- MCP tool changes don't need new tests — the wrapper is pure passthrough

Design decisions documented in plan file:
- atocore_remember deliberately doesn't bypass triage (quality gate)
- Detector is passive (surfaces proposals) not active (auto-registers)
- Sensible ingest-root defaults ("vault:incoming/projects/<id>/")
  so registration is one-click with no file-path thinking
- Extension adds 90 days rather than clearing expiry (gradual
  permanence earned through sustained reinforcement)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/atocore_mcp.py

@@ -243,6 +243,72 @@ def _tool_projects(args: dict) -> str:
     return "\n".join(lines)
 
 
+def _tool_remember(args: dict) -> str:
+    """Phase 6 Part B — universal capture from any Claude session.
+
+    Wraps POST /memory to create a candidate memory tagged with
+    source='mcp-remember'. The existing 3-tier triage is the quality
+    gate: nothing becomes active until sonnet (+ opus if borderline)
+    approves it. Returns the memory id so the caller can reference it
+    in the same session.
+    """
+    content = (args.get("content") or "").strip()
+    if not content:
+        return "Error: 'content' is required."
+
+    memory_type = (args.get("memory_type") or "knowledge").strip()
+    valid_types = ["identity", "preference", "project", "episodic", "knowledge", "adaptation"]
+    if memory_type not in valid_types:
+        return f"Error: memory_type must be one of {valid_types}."
+
+    project = (args.get("project") or "").strip()
+    try:
+        confidence = float(args.get("confidence") or 0.6)
+    except (TypeError, ValueError):
+        confidence = 0.6
+    confidence = max(0.0, min(1.0, confidence))
+
+    valid_until = (args.get("valid_until") or "").strip()
+    tags = args.get("domain_tags") or []
+    if not isinstance(tags, list):
+        tags = []
+    # Normalize tags: lowercase, dedupe, cap at 10
+    clean_tags: list[str] = []
+    for t in tags[:10]:
+        if not isinstance(t, str):
+            continue
+        t = t.strip().lower()
+        if t and t not in clean_tags:
+            clean_tags.append(t)
+
+    payload = {
+        "memory_type": memory_type,
+        "content": content,
+        "project": project,
+        "confidence": confidence,
+        "status": "candidate",
+    }
+    if valid_until:
+        payload["valid_until"] = valid_until
+    if clean_tags:
+        payload["domain_tags"] = clean_tags
+
+    result, err = safe_call(http_post, "/memory", payload)
+    if err:
+        return f"AtoCore remember failed: {err}"
+
+    mid = result.get("id", "?")
+    scope = project if project else "(global)"
+    tag_str = f" tags=[{', '.join(clean_tags)}]" if clean_tags else ""
+    expires = f" valid_until={valid_until}" if valid_until else ""
+    return (
+        f"Remembered as candidate: id={mid}\n"
+        f"  type={memory_type} project={scope} confidence={confidence:.2f}{tag_str}{expires}\n"
+        f"Will flow through the standard triage pipeline within 24h "
+        f"(or on next auto-process button click at /admin/triage)."
+    )
+
+
 def _tool_health(args: dict) -> str:
     """Check AtoCore service health."""
     result, err = safe_call(http_get, "/health")
@@ -527,6 +593,58 @@ TOOLS = [
         },
         "handler": _tool_memory_create,
     },
+    {
+        "name": "atocore_remember",
+        "description": (
+            "Save a durable fact to AtoCore's memory layer from any conversation. "
+            "Use when the user says 'remember this', 'save that for later', "
+            "'don't lose this fact', or when you identify a decision/insight/"
+            "preference worth persisting across future sessions. The fact "
+            "goes through quality review before being consulted in future "
+            "context packs (so durable facts get kept, noise gets rejected). "
+            "Call multiple times if one conversation has multiple distinct "
+            "facts worth remembering — one tool call per atomic fact. "
+            "Prefer 'knowledge' type for cross-project engineering insights, "
+            "'project' for facts specific to one project, 'preference' for "
+            "user work-style notes, 'adaptation' for standing behavioral rules."
+        ),
+        "inputSchema": {
+            "type": "object",
+            "properties": {
+                "content": {
+                    "type": "string",
+                    "description": "The atomic fact to remember. Under 250 chars. Should stand alone without session context.",
+                },
+                "memory_type": {
+                    "type": "string",
+                    "enum": ["identity", "preference", "project", "episodic", "knowledge", "adaptation"],
+                    "default": "knowledge",
+                },
+                "project": {
+                    "type": "string",
+                    "description": "Project id if scoped. Empty for cross-project. Unregistered names flagged by triage as 'emerging project' proposals.",
+                },
+                "confidence": {
+                    "type": "number",
+                    "minimum": 0,
+                    "maximum": 1,
+                    "default": 0.6,
+                    "description": "0.5-0.7 typical. 0.8+ only for ratified/committed claims.",
+                },
+                "valid_until": {
+                    "type": "string",
+                    "description": "ISO date YYYY-MM-DD if time-bounded (e.g. current state, scheduled event, quote expiry). Empty for permanent facts.",
+                },
+                "domain_tags": {
+                    "type": "array",
+                    "items": {"type": "string"},
+                    "description": "Lowercase topical tags (optics, thermal, firmware, procurement, etc.) for cross-project retrieval. 2-5 tags typical.",
+                },
+            },
+            "required": ["content"],
+        },
+        "handler": _tool_remember,
+    },
     {
         "name": "atocore_project_state",
         "description": (