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/crates/memoryd/src/lib.rs

@@ -0,0 +1,4 @@
+//! The memory role: the memory files, their index, and every memory tool call (M5a spec).
+
+pub mod config;
+pub mod socket;