Plan M5a: local memory in 15 tasks

memoryd (files, the check, edits, journal, index, recall, serving),
the memory tools and built-in grants in brokerd, the memory block in
loopd, bxctl reindex and memory, and the device checks with memoryd.

Each task was built as a reference and gated. Each was replayed on its
own at its end state (854 to 936 tests) and mutation-checked. Each
skeleton compiles and fails its tests. Every todo comment was read
beside its signature.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/plans/M5a/files/runbook-memory-index-damaged.md

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+## memory-index-damaged
+
+**What you see.** `recall` fails with a line starting `index:`, or `memoryd` logs one at start.
+
+**Why.** `index/memory.sqlite3` could not be read or written. It is disposable: everything in it
+comes from `sessions/` and `memory/notes.md`.
+
+**Confirm.** `ls -l <home>/index/`; the end of `memoryd`'s log.
+
+**Fix.** `bxctl reindex`, which builds a new index beside the old one and replaces it. If that
+fails too, stop `memoryd`, move `index/memory.sqlite3` aside, and start `memoryd`, which rebuilds
+it.
+
+**Check.** `bxctl reindex` prints how many logs, records and notes it read.