session-memory Phase 0: ingest cursor + sweep entrypoint + config (T06)

- session_memory/core/cursor.py: size/mtime change detection sidecar
- session_memory/config.toml: store paths, retention caps, per-source
  globs (claude on, codex/grok off for Phase 1), repo->domain map
- session_memory/ingest.py: discover->normalize->store->digest->evict;
  --dry-run creates/writes nothing; python -m session_memory.ingest
- tests/test_ingest.py; live dry-run parsed 84/85 real local sessions

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

workplans/AGENTIC-WP-0002-session-memory-phase0.md

@@ -103,7 +103,7 @@ synthetic sessions and tiny caps.
 
 ```task
 id: AGENTIC-WP-0002-T06
-status: progress
+status: done
 priority: medium
 state_hub_task_id: "a4b35c76-154d-4e99-b6d0-61cb6e47ecc0"
 ```
@@ -118,7 +118,7 @@ intended `cadence` trigger (`/schedule` daily/weekly) in the repo docs.
 
 ```task
 id: AGENTIC-WP-0002-T07
-status: todo
+status: progress
 priority: medium
 state_hub_task_id: "98d5cc7c-c285-4556-91a3-a85e0a2bb6df"
 ```