M9: MCP Hub locale/correlation propagation, real Hub health check, fix stale test image

Fixed two concrete gaps in the MCP knowledge-search endpoint: no locale field
existed at all (now nl-BE/en-GB/fr-BE, wired to the knowledge provider's
existing language param), and the correlation ID was always freshly minted,
ignoring any inbound X-Correlation-Id header. Added a shared dependency and
applied it to all four MCP endpoints so Fleet Ops's own audit log preserves
the Hub's real correlation ID end to end.

MCP_HUB_BASE_URL/MCP_PROVIDER_ID were declared in .env.example but never read
anywhere. Since the Hub's own registration is catalog-driven (it never needs
Fleet Ops to push a registration call), wired mcp_hub_base_url for a real Hub
reachability health check instead of an unneeded self-registration call.

Renamed Fleet Ops's own internal audit tool labels mobilityops_* -> fleet_ops_*
(mirrored in contracts/mcp-tools.json with mobilityops_* kept as deprecated
aliases); documented that the live Hub connector's own dotted tool namespace
is a separate, Hub-owned naming layer, deliberately not touched.

Automation page's MCP card now shows real evidence (last tool/client/count/
timestamp, honest no-evidence state) instead of just the registration flag.

Also fixed a real methodology gap found mid-session: compose.yaml's api
service has no bind mount, so `docker compose run --rm api` silently tests a
stale image until rebuilt. Re-ran every local gate after rebuilding; fixed one
genuinely stale test assertion and two lint line-length errors surfaced by
that rebuild. 176 tests passing, ruff clean, mypy clean (50 files).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/app/core/config.py

@@ -39,6 +39,11 @@ class Settings(BaseSettings):
     knowledge_dir: str = "/app/knowledge/procedures"
     mcp_hub_service_token: str = "replace-me-mcp-hub-token"
     mcp_hub_registration_enabled: bool = False
+    # MCP Hub's own registration is catalog-driven on the Hub side (the Hub reconciles
+    # its catalog into the gateway; Fleet Ops never pushes a registration call), so
+    # these are only used for an honest reachability health check, not self-registration.
+    mcp_hub_base_url: str = ""
+    mcp_provider_id: str = "fleet-ops"
     cors_allow_origins: str = "http://localhost:1228"
     demo_organization_name: str = "Northstar Mobility"
     demo_timezone: str = "Europe/Brussels"