Phase 17: map & fog VTT overhaul + player-facing projection

- Pure geometry library src/lib/map/* (grid, distance 5e/pf2e/euclid, AoE
  circle/cone/line/square, polygon rasterize + point-in-polygon, brush, fog set
  algebra, player projection) with unit tests.
- Schema: map tokens gain size/kind/characterId/hp/conditions/gmOnly; maps gain
  drawings/gridUnit(feet)/gridType/fogVersion + point/drawing sub-schemas. Dexie v8
  additive migration; mapsRepo.get + transactional mutate.
- Editor split into a shared MapCanvas renderer + MapEditor tool state machine:
  fog via brush/rectangle/polygon (+ size, reveal-all/hide-all), measurement
  (system-aware distance in feet), AoE templates (circle/cone/line/square preview),
  drawing annotations (freehand/line/arrow/rect/circle/text, GM-only), pings, and
  richer tokens (NxN size, character link with live HP ring, condition dots, edit popover).
- Player-facing projection: toPlayerProjection strips GM-only content; PlayerMapView
  renders it read-only with opaque fog; uiStore.activeMapId + 'Show to players'; the
  player view now shows the live battle map. enemyStatus extracted to
  src/lib/combat/playerProjection.ts (reused, and for Phase 18).

9 geometry unit tests; maps e2e covers upload→token→reveal-all→player projection.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/lib/db/repositories.ts

@@ -299,9 +299,20 @@ export const mapsRepo = {
     await db.maps.add(map);
     return map;
   },
+  get(id: string): Promise<BattleMap | undefined> {
+    return db.maps.get(id);
+  },
   async save(map: BattleMap): Promise<void> {
     await db.maps.put(battleMapSchema.parse({ ...map, updatedAt: now() }));
   },
+  /** Transactional read-modify-write (mirrors encountersRepo.mutate). */
+  async mutate(id: string, fn: (m: BattleMap) => BattleMap): Promise<void> {
+    await db.transaction('rw', db.maps, async () => {
+      const current = await db.maps.get(id);
+      if (!current) return;
+      await db.maps.put(battleMapSchema.parse({ ...fn(current), updatedAt: now() }));
+    });
+  },
   async remove(id: string): Promise<void> {
     await db.maps.delete(id);
   },