Phase 2: Terrain textures, bezier routing, drag-paint, HTTPS

- svg/renderer.ts: Full Canvas rendering engine with terrain textures
  (trees for forest, waves for water, peaks for mountains, contour
  lines for hills, hatch for farmland, buildings for settlements)
- Linear features: paired-edge bezier routing (straight-through,
  curves, dead-ends), river wobble, proper coastline along hex edges
- Drag-paint: click-and-drag in Paint mode paints multiple hexes,
  disables map panning during paint gesture
- NGINX reverse proxy + Let's Encrypt cert for hexifyer.davoryn.de
- Refactored hex-layer.ts to delegate rendering to renderer module

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

vite.config.ts

@@ -13,6 +13,7 @@ export default defineConfig({
   },
   server: {
     port: 5173,
+    allowedHosts: ['hexifyer.davoryn.de'],
     proxy: {
       '/api': {
         target: 'http://localhost:3001',