fix(omniroute): add required WS bridge secret, memory ceiling, shutdown grace period

Cross-checked the deployment against OmniRoute's own docs
(docs/reference/ENVIRONMENT.md, docs/guides/DOCKER_GUIDE.md) and found
three gaps from the original migration:

- OMNIROUTE_WS_BRIDGE_SECRET was entirely missing - ENVIRONMENT.md marks
  it REQUIRED (production), for the internal Codex Responses WebSocket
  bridge. docker compose config validated fine without it (compose
  doesn't know omniroute's own required-var list), so this went
  unnoticed until checking the docs directly.
- No mem_limit/OMNIROUTE_MEMORY_MB - the Docker guide is explicit that
  the 1024MB default heap is dashboard-only sized; coding-agent workloads
  (every client this stack has) need OMNIROUTE_MEMORY_MB=8192 and a
  10+ GiB container ceiling. Set both.
- No stop_grace_period - the guide's --stop-timeout 40 equivalent, so
  SQLite WAL changes checkpoint back into the main DB file on shutdown
  instead of getting killed mid-write.

Redis checked and confirmed correctly absent - OmniRoute uses SQLite
only, no Redis anywhere in its docs.

Still open: whether API_PORT actually isolates /dashboard and /api/*
from the published port, or bridges everything through (see issue #31)
- OmniRoute's own ARCHITECTURE.md doesn't document split-port mode as a
real security boundary, and the live "[API Bridge] ... -> dashboard"
log line is ambiguous. Waiting on a live curl test against
proxy-ai.home before treating that as resolved.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VPZ6TogJiYxG8E4EQBB197

docker-compose.yml

@@ -84,6 +84,15 @@ services:
       # default (SSRF guard against public-provider spoofing).
       - OMNIROUTE_ALLOW_PRIVATE_PROVIDER_URLS=true
       - OMNIROUTE_ALLOW_LOCAL_PROVIDER_URLS=true
+      # Required (production) per docs/reference/ENVIRONMENT.md — shared
+      # secret for the internal Codex Responses WebSocket bridge. Missed on
+      # first pass; docker-compose config validated fine without it, but
+      # the docs are explicit this one's required, not optional.
+      - OMNIROUTE_WS_BRIDGE_SECRET=${OMNIROUTE_WS_BRIDGE_SECRET}
+      # Default heap (1024MB) is dashboard-only sized per OmniRoute's own
+      # Docker guide — every client here is a coding CLI, which needs the
+      # larger figure the guide recommends. Paired with mem_limit below.
+      - OMNIROUTE_MEMORY_MB=8192
     # Same reasoning as litellm's extra_hosts entry below — ai-stack's bridge
     # network can't resolve search.home on its own.
     extra_hosts:
@@ -95,6 +104,12 @@ services:
     # to also change omniroute's own internal port config to match.
     ports:
       - "${OMNIROUTE_PORT:-4000}:${OMNIROUTE_API_PORT:-20129}"
+    # 10+ GiB ceiling per OmniRoute's Docker guide, matching
+    # OMNIROUTE_MEMORY_MB=8192 above.
+    mem_limit: 10g
+    # SQLite WAL needs time to checkpoint back into the main DB file on
+    # shutdown — the Docker guide's --stop-timeout 40 equivalent.
+    stop_grace_period: 40s
     restart: unless-stopped
     networks: [ai-stack]
     # ponytail: TCP-connect check, not an HTTP /healthz GET — the image has