feat(tomtom_flow): TomTom Orbis vector flow-tile telemetry adapter + CENTRAL_TRAFFIC_FLOW (v0.9.3)

Third CENTRAL_TRAFFIC-family member, first telemetry traffic source. Polls a
configured tile coverage set (Idaho metros, z=10), fetches Orbis vector flow
tiles, decodes per-segment relative_speed + road geometry, emits one telemetry
Event per road segment per poll to the new CENTRAL_TRAFFIC_FLOW stream. Renders
as colored polylines (green free-flow -> red jam) on the /telemetry map.

Production code; supervisor + gui + ARCHIVE restart (NEW event-bearing stream
central.traffic_flow.> -> archive must resubscribe). Ships disabled; needs a
"tomtom" api key in config.api_keys before enable.

- Subject central.traffic_flow.{z}.{x}.{y} (token traffic_flow, non-overlapping
  with central.traffic.>). category="flow.tomtom_flow" -> GUI event_type "flow".
- Severity from relative_speed: >=0.75=1, 0.5-0.75=2, 0.25-0.5=3, <0.25=4.
- Cadence 300s; 7-day retention (high-volume telemetry). Dedup minute-bucketed,
  inherited from the v0.9.1 SourceAdapter mixin.
- Shared tomtom_flow_parse module (decode + slippy-tile georeference) reused by
  the v0.9.4 on-demand passthrough endpoint.
- Generic framework change (Option A, ~3 lines, inert for the other 14
  adapters): Geo.geometry optional field + archive _build_geom_sql prefers it,
  so segments persist their real LineString to the PostGIS geom column.
- Idaho-only (Orbis tier confirmed live). Cameras + Navi passthrough are follow-ups.
- deps: mapbox-vector-tile (vector PBF decode); itsdangerous promoted to an
  explicit dependency (gui/csrf.py + gui/wizard.py imported it as an undeclared
  transitive that uv re-lock would otherwise prune).

Full suite: 780 passed, 1 skipped (central and unprivileged zvx, 3x each).

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

src/central/gui/routes.py

@@ -2651,7 +2651,7 @@ ADAPTER_GROUPS = {
     "Space": ["swpc_alerts", "swpc_kindex", "swpc_protons"],
     "Geophysical": ["usgs_quake", "nwis"],
     "Earth Observation": ["eonet"],
-    "Transportation": ["wzdx", "state_511_atis"],
+    "Transportation": ["wzdx", "state_511_atis", "tomtom_flow"],
 }
 # Same palette the map legend uses, indexed by sorted-adapter position.
 EVENTS_PALETTE = [