Stabilize sanitizer lanes and daemon concurrency (#40)
* fix(repair): keep RPC progress alive
* fix(daemon): propagate DB open failure to FSM and add shutdown cancellation
* fix(db): classify FTS5 inverted-index errors as repairable, not transient locks
* fix(daemon): clean up stale corrupt files after salvage and suppress optional readiness keys
* test(db_recovery): update FTS5 classification test for new transient-lock exclusion
* test(gc): add garbage collector unit tests for collection, dry-run, scheduling
* test(repair): expand repair manager tests with hash-verified recovery and source ordering
* fix(gc): dry-run mode no longer increments blocksDeleted/bytesReclaimed
* fix(mock,mcp): add atomic bool for lock consistency, move field assignments
* style: fix unnecessary-copy, dead-store, and const-refable findings from Infer
* fix(daemon): increase default shutdown timeout from 15s to 120s
* fix(daemon): demote non-critical warnings to info (FTS5, VACUUM, WorkCoordinator timeout)
* fix(db): re-enable WAL auto-checkpoint to prevent unbounded WAL growth
* test(pool): add WAL auto-checkpoint and concurrency coverage for connection pool
* test(pool): add exhaustion, stats, lifecycle, and read-only connection pool tests
* test(pool): add tagging, WAL journal, reuse, and busy timeout tests
* test(metrics): relax session snippet assertion to tolerate stub behavior
* fix(test): stabilize sanitizer triage failures
* fix(build): wire version and zyp deps
* fix(daemon): close TSAN race clusters
* fix(test): guard optional zyp dep
* fix(test): address PR review findings
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