feat: Minecraft Clone MVP – prozedurale Welt, Blöcke, Abbauen/Setzen

- Weltgenerierung: FBM-Terrain, 3 Biome (Plains/Wald/Wüste), Höhlen, Wasser, Bäume
- Blöcke: Grass, Dirt, Stein, Sand, Holz, Blätter, Wasser (+Bedrock)
- Interaktion: DDA-Voxel-Raycast, Abbauen (LMB) & Setzen (RMB), Hotbar 1-6
- Spieler: First-Person, Gravitation, AABB-Kollision, Springen, Fly-Mode (F)
- Engine: Chunk-Streaming (16x16x64), Face-Culling, opaker+transparenter Pass
- Stack: Three.js + simplex-noise via CDN, prozedurale Texturen, kein Build-Step

Co-Authored-By: Claude <noreply@anthropic.com>

js/raycast.js

@@ -0,0 +1,50 @@
+// DDA-Voxel-Raycast (Amanatides & Woo). Liefert ersten getroffenen, soliden
+// (nicht Luft, nicht Wasser) Block sowie die Eintrittsnormale (face).
+import { BLOCK } from './constants.js';
+
+export function raycastVoxel(getBlock, originX, originY, originZ, dirX, dirY, dirZ, maxDist) {
+  let x = Math.floor(originX);
+  let y = Math.floor(originY);
+  let z = Math.floor(originZ);
+
+  const stepX = dirX > 0 ? 1 : dirX < 0 ? -1 : 0;
+  const stepY = dirY > 0 ? 1 : dirY < 0 ? -1 : 0;
+  const stepZ = dirZ > 0 ? 1 : dirZ < 0 ? -1 : 0;
+
+  const tDeltaX = stepX !== 0 ? Math.abs(1 / dirX) : Infinity;
+  const tDeltaY = stepY !== 0 ? Math.abs(1 / dirY) : Infinity;
+  const tDeltaZ = stepZ !== 0 ? Math.abs(1 / dirZ) : Infinity;
+
+  let tMaxX = stepX > 0 ? (x + 1 - originX) * tDeltaX
+           : stepX < 0 ? (originX - x) * tDeltaX : Infinity;
+  let tMaxY = stepY > 0 ? (y + 1 - originY) * tDeltaY
+           : stepY < 0 ? (originY - y) * tDeltaY : Infinity;
+  let tMaxZ = stepZ > 0 ? (z + 1 - originZ) * tDeltaZ
+           : stepZ < 0 ? (originZ - z) * tDeltaZ : Infinity;
+
+  let nx = 0, ny = 0, nz = 0;
+  let t = 0;
+
+  // Start-Voxel pruefen
+  let b = getBlock(x, y, z);
+  if (b !== BLOCK.AIR && b !== BLOCK.WATER) {
+    return { x, y, z, block: b, nx: 0, ny: 0, nz: 0 };
+  }
+
+  const maxSteps = 128;
+  for (let i = 0; i < maxSteps; i++) {
+    if (tMaxX < tMaxY && tMaxX < tMaxZ) {
+      x += stepX; t = tMaxX; tMaxX += tDeltaX; nx = -stepX; ny = 0; nz = 0;
+    } else if (tMaxY < tMaxZ) {
+      y += stepY; t = tMaxY; tMaxY += tDeltaY; nx = 0; ny = -stepY; nz = 0;
+    } else {
+      z += stepZ; t = tMaxZ; tMaxZ += tDeltaZ; nx = 0; ny = 0; nz = -stepZ;
+    }
+    if (t > maxDist) break;
+    b = getBlock(x, y, z);
+    if (b !== BLOCK.AIR && b !== BLOCK.WATER) {
+      return { x, y, z, block: b, nx, ny, nz };
+    }
+  }
+  return null;
+}