cleanup: QOL improvements — gitignore, Tags constants, remove debug artifacts

- Add .DS_Store, unused/, .vscode/settings.json to .gitignore
- Add .editorconfig (tabs for Lua, LF, UTF-8)
- Fix duplicate submodule entry in .gitmodules
- Add Tags table (player, tank, ground, granade, ammoCrate) — replace magic numbers
- Add SCREEN_W/SCREEN_H constants
- Fix leaked global variable `c` in Game.lua
- Remove Noble.showFPS = true from BomberScene
- Remove debug print() calls from granade, enemy, BomberScene
- Fix clean_build_dir glob bug in both build scripts
- Make PLAYDATE_SDK_PATH configurable via env var

.gitignore

@@ -1 +1,14 @@
-builds/*
+builds/
+source/assets/unused/
+
+# OS
+.DS_Store
+Thumbs.db
+
+# IDE (machine-specific)
+.vscode/settings.json
+
+# Editors
+*.swp
+*.swo
+*~