phase9 first-real-use validation + small hygiene wins

Session 1 of the four-session plan. Empirically exercises the Phase 9
loop (capture -> reinforce -> extract) for the first time and lands
three small hygiene fixes.

Validation script + report
--------------------------
scripts/phase9_first_real_use.py — reproducible script that:
  - sets up an isolated SQLite + Chroma store under
    data/validation/phase9-first-use (gitignored)
  - seeds 3 active memories
  - runs 8 sample interactions through capture + reinforce + extract
  - prints what each step produced and reinforcement state at the end
  - supports --json output for downstream tooling

docs/phase9-first-real-use.md — narrative report of the run with:
  - extraction results table (8/8 expectations met exactly)
  - the empirical finding that REINFORCEMENT MATCHED ZERO seeds
    despite sample 5 clearly echoing the rebase preference memory
  - root cause analysis: the substring matcher is too brittle for
    natural paraphrases (e.g. "prefers" vs "I prefer", "history"
    vs "the history")
  - recommended fix: replace substring matcher with a token-overlap
    matcher (>=70% of memory tokens present in response, with
    light stemming and a small stop list)
  - explicit note that the fix is queued as a follow-up commit, not
    bundled into the report — keeps the audit trail clean

Key extraction results from the run:
  - all 7 heading/sentence rules fired correctly
  - 0 false positives on the prose-only sample (the most important
    sanity check)
  - long content preserved without truncation
  - dedup correctly kept three distinct cues from one interaction
  - project scoping flowed cleanly through the pipeline

Hygiene 1: FastAPI lifespan migration (src/atocore/main.py)
- Replaced @app.on_event("startup") with the modern @asynccontextmanager
  lifespan handler
- Same setup work (setup_logging, ensure_runtime_dirs, init_db,
  init_project_state_schema, startup_ready log)
- Removes the two on_event deprecation warnings from every test run
- Test suite now shows 1 warning instead of 3

Hygiene 2: EXTRACTOR_VERSION constant (src/atocore/memory/extractor.py)
- Added EXTRACTOR_VERSION = "0.1.0" with a versioned change log comment
- MemoryCandidate dataclass carries extractor_version on every candidate
- POST /interactions/{id}/extract response now includes extractor_version
  on both the top level (current run) and on each candidate
- Implements the versioning requirement called out in
  docs/architecture/promotion-rules.md so old candidates can be
  identified and re-evaluated when the rule set evolves

Hygiene 3: ~/.git-credentials cleanup (out-of-tree, not committed)
- Removed the dead OAUTH_USER:<jwt> line for dalidou:3000 that was
  being silently rewritten by the system credential manager on every
  push attempt
- Configured credential.http://dalidou:3000.helper with the empty-string
  sentinel pattern so the URL-specific helper chain is exactly
  ["", store] instead of inheriting the system-level "manager" helper
  that ships with Git for Windows
- Same fix for the 100.80.199.40 (Tailscale) entry
- Verified end to end: a fresh push using only the cleaned credentials
  file (no embedded URL) authenticates as Antoine and lands cleanly

Full suite: 160 passing (no change from previous), 1 warning
(was 3) thanks to the lifespan migration.

src/atocore/api/routes.py

@@ -31,6 +31,7 @@ from atocore.interactions.service import (
     record_interaction,
 )
 from atocore.memory.extractor import (
+    EXTRACTOR_VERSION,
     MemoryCandidate,
     extract_candidates_from_interaction,
 )
@@ -622,6 +623,7 @@ def api_extract_from_interaction(
         "candidate_count": len(candidates),
         "persisted": payload.persist,
         "persisted_ids": persisted_ids,
+        "extractor_version": EXTRACTOR_VERSION,
         "candidates": [
             {
                 "memory_type": c.memory_type,
@@ -630,6 +632,7 @@ def api_extract_from_interaction(
                 "confidence": c.confidence,
                 "rule": c.rule,
                 "source_span": c.source_span,
+                "extractor_version": c.extractor_version,
             }
             for c in candidates
         ],