feat(game): wilting tomato mechanic replaces static light

Static guards now emit a Manhattan aura that shrinks by 1 per turn until
harmless (clamped at -1 to keep solver state finite). Level data schema
change: 'static' guards now take 'initialRadius' instead of 'litCells'.
All 27 static-guard entries migrated in one pass.

L1 and L2 redesigned with real forced-zigzag walls — solver path is now
20 moves (vs Manhattan 14), so players must move AWAY from the goal to
reach it. L2 adds three wilting tomatoes parked on the zigzag path as
a gentle intro to the mechanic.

Tests: +3 new tests on StaticGuard wilting behavior; all 70 tests pass.

docs/codebase-summary.md

@@ -103,7 +103,7 @@ NNTV is a turn-based stealth puzzle game built with Svelte 5 and Vite 6.x. The c
 
 ```
 Guard (abstract base: grid, row, col, type, direction, isOn)
-├── StaticGuard     — lights fixed litCells array
+├── StaticGuard     — wilting tomato: Manhattan aura shrinks by 1 per turn (initialRadius → currentRadius)
 ├── RotatingGuard   — rotates beam 90°/turn, castBeam with mirror bounce
 ├── BlinkingGuard   — toggles isOn, lights litCells when on
 ├── MirrorGuard     — lights own cell, stores reflectDirection (cw/ccw)
@@ -122,11 +122,12 @@ Guard (abstract base: grid, row, col, type, direction, isOn)
   goal: { row: 5, col: 5 },
   walls: [{ row: 1, col: 1 }, ...],
   guards: [
-    { type: "static", position: { row: 2, col: 4 }, litCells: [...] },
+    { type: "static", position: { row: 2, col: 4 }, initialRadius: 2 },
     { type: "rotating", position: { row: 3, col: 3 }, startDirection: 0 },
     { type: "blinking", position: {...}, litCells: [...], startState: true },
     { type: "mirror", position: {...}, reflectDirection: "cw" },
     { type: "patrolling", startPosition: {...}, path: [...] },
+    { type: "chaser", position: {...}, detectionRadius: 3 },
   ],
   isFinalLevel: false
 }