Initial commit: Arcanum TD — medieval fantasy tower defense

Vite + React + PixiJS + TypeScript. Features:
- 4-level campaign (King's Road → Obsidian Keep)
- Isometric 2.5D grid with ley-line mechanics
- ECS architecture (entities, components, systems)
- 4 tower types, hero spellcaster, 10+ enemy types
- Lich King boss with 3-phase AI
- Meta-progression: essence, rune unlocks
- Full UI redesign with fantasy design system

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tsconfig.json

@@ -0,0 +1,7 @@
+{
+  "files": [],
+  "references": [
+    { "path": "./tsconfig.app.json" },
+    { "path": "./tsconfig.node.json" }
+  ]
+}