feat(demo): add demo manifest, Dutch demo entry, permanent badge and About page

Adds GET /api/v1/demo/manifest as a single source of truth for the demo's
fictional org identity (Northstar Mobility -- surfacing the project's
already-locked tenant name), synthetic-data/reset state, and live scenario
readiness. Rewrites the login screen in Dutch with an honest, no-password
demo entry and a guided-demo entry point, replaces the loud full-width
demo banner with a subtle badge + popover, and adds a compact About page
explaining what's real vs. synthetic vs. not yet connected.

compose.yaml

@@ -34,6 +34,9 @@ services:
       N8N_WEBHOOK_URL: ${N8N_WEBHOOK_URL:-http://n8n:5678/webhook/mobilityops-return}
       N8N_CALLBACK_TOKEN: ${MOBILITYOPS_CALLBACK_TOKEN:-replace-me-n8n-callback-token}
       MCP_HUB_SERVICE_TOKEN: ${MCP_HUB_SERVICE_TOKEN:-replace-me-mcp-hub-token}
+      DEMO_ORGANIZATION_NAME: ${DEMO_ORGANIZATION_NAME:-Northstar Mobility}
+      DEMO_TIMEZONE: ${DEMO_TIMEZONE:-Europe/Brussels}
+      DEMO_ALLOW_RESET: ${DEMO_ALLOW_RESET:-true}
     ports:
       - "8128:8000"
     depends_on: