chore(docs+devops): cross-module doc sync + sprint archival moves + compose updates

Bundled pre-session doc + ops work:
- docs/modules/**: sync across advisory-ai, airgap, cli, excititor,
  export-center, findings-ledger, notifier, notify, platform, router,
  sbom-service, ui, web (architectural + operational updates)
- docs/features/**: updates to checked excititor vex pipeline,
  developer workspace, quick verify drawer
- docs top-level: README, quickstart, API_CLI_REFERENCE, UI_GUIDE,
  code-of-conduct/TESTING_PRACTICES updates
- docs/qa/feature-checks/: FLOW.md + excititor state update
- docs/implplan/: remaining sprint updates + new Concelier source
  credentials sprint (SPRINT_20260422_003)
- docs-archived/implplan/: 30 sprint archival moves (ElkSharp series,
  misc completed sprints)
- devops/compose: .env + services compose + env example + router gateway
  config updates

File-level granularity preserved.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

devops/compose/env/stellaops.env.example

@@ -20,6 +20,15 @@ POSTGRES_PASSWORD=stellaops           # Change for production
 POSTGRES_DB=stellaops_platform
 POSTGRES_PORT=5432
 
+# Shared connection strings consumed by docker-compose.stella-services.yml.
+# Keep these aligned with the local compose DNS aliases and bootstrap volumes.
+STELLAOPS_POSTGRES_CONNECTION=Host=db.stella-ops.local;Port=5432;Database=stellaops_platform;Username=stellaops;Password=stellaops;Maximum Pool Size=50
+STELLAOPS_POSTGRES_AUTHORITY_CONNECTION=Host=db.stella-ops.local;Port=5432;Database=stellaops_authority;Username=stellaops;Password=stellaops;Maximum Pool Size=20;Minimum Pool Size=2
+
+# Shared mounts referenced by service definitions.
+STELLAOPS_CERT_VOLUME=../../etc/authority/keys:/app/etc/certs:ro
+STELLAOPS_CA_BUNDLE_VOLUME=./combined-ca-bundle.crt:/etc/ssl/certs/ca-certificates.crt:ro
+
 # Valkey (Redis-compatible cache and messaging)
 VALKEY_PORT=6379
 
@@ -37,6 +46,9 @@ ROUTER_GATEWAY_CONFIG=./router-gateway-local.json
 # Authority claims override endpoint base URL consumed by router-gateway.
 ROUTER_AUTHORITY_CLAIMS_OVERRIDES_URL=http://authority.stella-ops.local
 
+# HMAC-SHA256 signing key for gateway identity envelopes used in local compose.
+STELLAOPS_IDENTITY_ENVELOPE_SIGNING_KEY=xPGV6S6dlS3JsLw3DuPRAEAXqJ9JOsfWE/8oIiplGRk=
+
 # =============================================================================
 # CORE SERVICES
 # =============================================================================