feat(server): compose OMNIGRAPH_TARGET_URI with OMNIGRAPH_CONFIG in entrypoint (#129)

The container entrypoint's URI and config branches were mutually
exclusive, so a deployment driven by OMNIGRAPH_TARGET_URI could never
load a policy file. Forward --config alongside the positional URI when
OMNIGRAPH_CONFIG is also set (the URI still wins via resolve_target_uri),
enabling Cedar policy without changing how the URI is provided.

Add docker/entrypoint_test.sh (arg-composition cases) + a CI job, and
document the env-var contract in docs/user/deployment.md.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -111,6 +111,18 @@ jobs:
       - name: Verify AGENTS.md ↔ docs/ cross-links
         run: bash scripts/check-agents-md.sh
 
+  entrypoint_test:
+    name: Container Entrypoint
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    steps:
+      - name: Checkout source
+        uses: actions/checkout@v5.0.1
+
+      - name: Verify omnigraph-server entrypoint arg composition
+        run: sh docker/entrypoint_test.sh
+
   test:
     name: Test Workspace
     needs: classify_changes