docs: compose files, Dockerfile, CI workflow, README and ci-requirements describe the build, briefly

Comment-only pilot for the comment standard (rule 32, milestone 544).
Issue and rule numbers, dates, run ids and incident stories come out;
the constraint each one guarded stays as a present-tense sentence.

History removed from the files, kept here:
- Dockerfile/CI: installing from uv.lock replaced pip/uv-pip installs that
  ignored the lock (#2194, the mcp 2.0.0 break on 2026-07-28); --locked
  then caught pgvector missing from the lock.
- CI: plugin paths were added after #2198/#2209 reached a live install;
  `integration` joined the build's needs after run 8212 published
  :latest with integration red (#4958); the `[[ ]]` tag step failed
  silently on dash (2a374d9); BUILD_VERSION carried the channel until
  2026-08-31 (#3298).
- jq was removed from the hooks in #4107.
- prod compose: the lenient DB healthcheck followed a runc setns crash
  loop; pgvector arrived with migration 0067 via a PG16->17 dump/restore.

Corrections to match the code: README names the Settings tab
"MCP Access"; ci-requirements says the Dockerfile builds on node:22
and lint covers scripts/.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docker-compose.prod.yml

@@ -21,10 +21,7 @@ services:
         max_attempts: 5
 
   db:
-    # pgvector image (Debian/glibc, PG17) — bundles the `vector` extension that
-    # migration 0067 enables. Moved off postgres:16-alpine via logical
-    # dump/restore (which doubles as the PG16->PG17 major upgrade); see the
-    # TRANSITION runbook in the PR.
+    # Postgres 17 with the vector extension Scribe needs.
     image: pgvector/pgvector:pg17
     stop_grace_period: 120s
     volumes:
@@ -35,9 +32,8 @@ services:
       POSTGRES_DB: scribe
     networks:
       - scribe_backend
-    # Lenient by design: a transient host exec/healthcheck stall (incident:
-    # runc setns failures -> "unhealthy" -> SIGKILL -> crash loop) must never
-    # escalate to killing the DB. Health here only gates app startup order.
+    # Lenient on purpose: health only orders app startup, so a stalled check
+    # must not get the database killed.
     healthcheck:
       test: ["CMD-SHELL", "pg_isready -U scribe"]
       interval: 30s