docs: Day 5 — extractor scope + stale follow-ups cleaned

Documents the LLM-assisted extractor's in-scope / out-of-scope
categories derived from the first live triage pass (16 promoted,
35 rejected). Five in-scope classes, six explicit out-of-scope
classes, trust model summary, multi-model future direction.

Cleaned up stale follow-up items in next-steps.md: rule expansion
marked deprioritized, LLM extractor marked done, retrieval harness
marked done with expansion pending.

Fixed docstring timeout (45s -> 90s) in extractor_llm.py.

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

src/atocore/memory/extractor_llm.py

@@ -29,7 +29,7 @@ Configuration:
 - ``ATOCORE_LLM_EXTRACTOR_MODEL`` overrides the model alias (default
   ``haiku``).
 - ``ATOCORE_LLM_EXTRACTOR_TIMEOUT_S`` overrides the per-call timeout
-  (default 45 seconds — first invocation is slow because Node.js
+  (default 90 seconds — first invocation is slow because Node.js
   startup plus OAuth check is non-trivial).
 
 Implementation notes: