feat: task 2.5 MapPositions (clustered + selected sources)

- src/data/devices.ts: useDevicesById() — TanStack Query (5-min stale)
  returning Map<deviceId, Device>. deviceLabel() formats human-readable
  titles ("FMB920 #3458").
- src/map/layers/map-positions.tsx: <MapPositions /> side-effect-only.
  Two GeoJSON sources (clustered non-selected + unclustered selected).
  Five layers: non-selected symbol + direction + cluster-bubble,
  selected symbol + direction. Click handlers: marker -> selectDevice,
  cluster -> getClusterExpansionZoom + easeTo. Hover toggles cursor.
- src/routes/_authed/monitor.tsx: renders <MapPositions /> inside
  <MapView>.

Schema overhaul in src/auth/client.ts:
- Made Schema SDK-compatible. Each entry is an *array* of row types
  (devices: DeviceRow[], not just DeviceRow). RegularCollections<Schema>
  filters on array-like values; non-arrays collapse to never which
  broke readItems('devices', ...) with keyof Schema = never.
- Spelled out the composed client type as DirectusClient<Schema> &
  RestClient<Schema> & AuthenticationClient<Schema> — without the
  explicit annotation Schema didn't flow through .with(...) chain to
  request() call sites.
- Added DeviceRow + EventRow types; exported via @/auth.

useDevicesById uses readItems<Schema, 'devices', Query<Schema, DeviceRow>>
— explicit generics because the SDK doesn't infer Schema from the
receiver's type at call sites.

Deviations:
1. Spec referenced device.kind for category — Phase 1 schema doesn't
   have it yet; everything maps to 'default'. Refine when kind lands.
2. Cluster bubble uses 'default-neutral' sprite instead of a dedicated
   'cluster-background' (not in 2.3's registry). Swap in 3.8.
3. getClusterExpansionZoom is Promise-based in maplibre-gl 5.x (was
   callback-style); used .then().

Bundle: main bundle 394KB / 120KB gz, ~1KB up from 2.4. /monitor
chunk includes the new layer module (~10KB).

.planning/phase-2-live-map/README.md

@@ -52,7 +52,7 @@ When Phase 2 is done:
 | 2.2 | [Tile-source switcher](./02-tile-source-switcher.md)                                       | 🟩     |
 | 2.3 | [Sprite preload (racing categories)](./03-sprite-preload.md)                               | 🟩     |
 | 2.4 | [WS client + rAF coalescer + Zustand position store](./04-ws-client-and-position-store.md) | 🟩     |
-| 2.5 | [MapPositions (clustered + selected sources)](./05-map-positions.md)                       | ⬜     |
+| 2.5 | [MapPositions (clustered + selected sources)](./05-map-positions.md)                       | 🟩     |
 | 2.6 | [MapTrails (bounded ring buffer, polyline rendering)](./06-map-trails.md)                  | ⬜     |
 | 2.7 | [Event picker (subscription driver)](./07-event-picker.md)                                 | ⬜     |
 | 2.8 | [Camera control trio](./08-camera-trio.md)                                                 | ⬜     |