Phase 1: Core hex engine, Leaflet overlay, terrain painting UI

- core/: Pure TS hex engine (axial coords, hex grid, terrain types,
  edge connectivity with constraint solver, HexMap state model)
- src/map/: Leaflet L.CRS.Simple map init, Canvas-based hex overlay
  layer (L.GridLayer), click/edge interaction detection
- src/ui/: Sidebar with toolbar (Select/Paint/Feature modes),
  terrain picker, hex inspector, map settings (hex size, grid, opacity)
- pipeline/: Tile pyramid generator (sharp, from source image)
- tests/: 32 passing tests for coords, hex-grid, edge-connectivity
- Uses Kiepenkerl tiles (symlinked) for development

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/core/hex-grid.test.ts

@@ -0,0 +1,50 @@
+import { describe, it, expect } from 'vitest';
+import { getHexesInBounds, hexAtPixel } from '@core/hex-grid';
+
+describe('getHexesInBounds', () => {
+  const size = 32;
+
+  it('returns hexes covering a small area', () => {
+    const hexes = getHexesInBounds(
+      { minX: 0, minY: 0, maxX: 100, maxY: 100 },
+      size,
+    );
+    expect(hexes.length).toBeGreaterThan(0);
+  });
+
+  it('includes origin hex when bounds contain origin', () => {
+    const hexes = getHexesInBounds(
+      { minX: -10, minY: -10, maxX: 10, maxY: 10 },
+      size,
+    );
+    const hasOrigin = hexes.some(h => h.q === 0 && h.r === 0);
+    expect(hasOrigin).toBe(true);
+  });
+
+  it('more hexes for larger area', () => {
+    const small = getHexesInBounds(
+      { minX: 0, minY: 0, maxX: 100, maxY: 100 },
+      size,
+    );
+    const large = getHexesInBounds(
+      { minX: 0, minY: 0, maxX: 500, maxY: 500 },
+      size,
+    );
+    expect(large.length).toBeGreaterThan(small.length);
+  });
+
+  it('smaller hex size yields more hexes', () => {
+    const bounds = { minX: 0, minY: 0, maxX: 200, maxY: 200 };
+    const big = getHexesInBounds(bounds, 64);
+    const small = getHexesInBounds(bounds, 16);
+    expect(small.length).toBeGreaterThan(big.length);
+  });
+});
+
+describe('hexAtPixel', () => {
+  it('origin pixel maps to origin hex', () => {
+    const coord = hexAtPixel({ x: 0, y: 0 }, 32);
+    expect(coord.q).toBe(0);
+    expect(coord.r).toBe(0);
+  });
+});