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>

frontend/src/i18n/locales/en-GB/integrations.json

@@ -15,7 +15,11 @@
     "gatewayKicker": "Tool gateway",
     "mcpTitle": "MCP Hub",
     "mcpEnabled": "Registration is enabled for this deployment.",
-    "mcpNotConnected": "Not yet connected — prepared for future controlled tool calls from the Hub."
+    "mcpNotConnected": "Not yet connected — prepared for future controlled tool calls from the Hub.",
+    "mcpNoEvidence": "Registered, but no tool call has been recorded yet.",
+    "mcpEvidence": "Last call: {{tool}} by {{client}} · {{count}} total calls",
+    "mcpHubReachable": "Hub reachable",
+    "mcpHubUnreachable": "Hub unreachable"
   },
   "statusLabels": {
     "notConnected": "Not connected",