Initial release: PokeRogue Type Effectiveness extension

Chrome/Firefox MV3 extension that shows move type effectiveness during
PokeRogue battles. Features:

- Auto-detects battle state via Phaser game bridge (MAIN world)
- Shows effectiveness multiplier, base power, and physical/special category
- Supports single and double battles
- Manual type calculator mode as fallback
- Draggable overlay with dark theme matching PokeRogue aesthetic
- Settings popup with position, opacity, and display options
- Complete Gen 6+ type chart (18 types) from PokeRogue source data
- Type colors matching PokeRogue's own color scheme

.gitignore

@@ -0,0 +1,19 @@
+# OS files
+.DS_Store
+Thumbs.db
+
+# IDE
+.vscode/
+.idea/
+*.swp
+*.swo
+
+# Temp
+*.log
+*.tmp
+
+# Node (not used, but just in case)
+node_modules/
+
+# Config
+opencode.json