chore: harden docker-compose deployment (bind, memory limits, no-new-privileges)

- frontend publishes on ${FRONTEND_PUBLISH_ADDR:-127.0.0.1} not 0.0.0.0 (M4).
- mem_limit on backend(4g)/postgres(1g)/frontend(512m), .env-overridable (M3).
- security_opt: no-new-privileges on app + postgres services.
New knobs documented + allowlisted in the config meta-test; compose validates.
Deferred (need host verification): image pinning, backend healthcheck, cap_drop
on postgres/tor, Postgres backup sidecar.

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

.env.example

@@ -427,3 +427,14 @@ VISION_MANAGER_DATABASE_URL=
 # VISION_MEM_LOW_WATERMARK_PCT  used% >= this → inhibit starts (keep HIGH - LOW >= ~10 so the band beats jitter). Default 80.
 # VISION_MEM_YIELD_COOLDOWN     Seconds after a pressure-stop during which restart is refused regardless of backlog. Default 300.
 # VISION_MEM_POLL_INTERVAL      Mem sub-poll cadence, seconds (<= VISION_POLL_INTERVAL); catches spikes between backlog ticks. Default 5.
+
+# ---- Deployment resource bounds & exposure (docker-compose.yml) ----
+# Host interface the frontend port publishes on. Default 127.0.0.1 so SvelteKit
+# (plain HTTP) is reachable only by a host-local reverse proxy. Set 0.0.0.0 only
+# if your TLS terminator runs on a different host.
+FRONTEND_PUBLISH_ADDR=127.0.0.1
+# Per-container memory ceilings (docker mem_limit). Generous defaults; tune to
+# your host. The backend runs OCR + headless Chromium and is the heavy one.
+BACKEND_MEM_LIMIT=4g
+FRONTEND_MEM_LIMIT=512m
+POSTGRES_MEM_LIMIT=1g