feat: task 2.8 camera control trio + follow toggle

- src/map/core/map-pref-store.ts: mapFollow boolean (default true) +
  setter. Persisted via trm-map-prefs.
- src/map/core/camera/default-camera.tsx: <MapDefaultCamera /> fits
  the snapshot's bounds once per activeEventId change. Uses a
  fittedFor ref; resets to null when activeEventId becomes null.
  Single-point events centre+zoom 12; multi-point fitBounds with
  padding capped at min(canvas*0.1, 80).
- src/map/core/camera/selected-device.tsx: <MapSelectedDevice />
  pans+zooms on selection change, smooth pans on subsequent position
  updates with mapFollow on. Separate effect listens for user-gesture
  movestart (originalEvent truthy) and flips mapFollow off.
- src/map/core/camera/map-camera.tsx: <MapCamera coordinates> imperative
  one-shot. Phase 2 doesn't use it; primitive for replay (Phase 4) and
  future "fit to all" UI.
- src/map/core/follow-toggle.tsx: <FollowToggle /> icon-button using
  Lucide Locate/LocateOff. Sits below the trails toggle.
- src/routes/_authed/monitor.tsx: renders FollowToggle, MapDefaultCamera,
  MapSelectedDevice.

Deviations:
- Manual-pan listener uses an inline { originalEvent?: unknown } type
  instead of MapLibre's MapMouseEvent|MapTouchEvent union (typing
  friction across version bumps).
- MapDefaultCamera clears fittedFor on activeEventId === null so
  re-selecting the same event later re-fits.

Bundle: main 395KB / 120KB gz, no measurable change.

.planning/phase-2-live-map/07-event-picker.md

@@ -188,8 +188,8 @@ Three new files plus orchestration in the monitor route:
   3. `subscribe('event:<new>')`.
   4. On success → `applySnapshot(eventId, snapshot)` + persist to `localStorage`.
   5. On failure → `console.warn` and leave previous state alone.
-  Out-of-order safety via per-call version counter; `null` clears the active event.
-  Plus `readSavedActiveEventId()` for callers that want to know what the persisted choice is.
+     Out-of-order safety via per-call version counter; `null` clears the active event.
+     Plus `readSavedActiveEventId()` for callers that want to know what the persisted choice is.
 - **`src/ui/components/event-picker.tsx`** — `<EventPicker activeEventId, onChange>`. Click-to-open dropdown with click-outside-to-close. Shows the events list sorted most-recent-first; each row displays name + date + discipline. Disabled state when loading / errored / empty.
 - **`src/live/index.ts`** — re-exports `useActiveEventOrchestration` + `readSavedActiveEventId`.
 - **`src/routes/_authed/monitor.tsx`** — orchestration:
@@ -204,6 +204,7 @@ Three new files plus orchestration in the monitor route:
 3. Logout-clears-saved-event-id: documented as a Phase 1 follow-up in this task's risks section. Not implemented here — `performLogout` (Phase 1.8) doesn't currently clear localStorage. A small follow-up patch will pull `localStorage.removeItem('trm-active-event-id')` into the logout flow.
 
 **Smoke check (local `pnpm dev`):**
+
 - `/monitor` shows the event picker top-left. Clicking it opens the dropdown with the seeded events.
 - On a fresh page load (with stage Directus reachable + a connected WS): the dogfood event auto-selects within ~1s; the snapshot of seeded positions appears as map markers.
 - Switching events: previous event's markers disappear, new event's markers appear, no leftover state.