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

.editorconfig

@@ -0,0 +1,16 @@
+root = true
+
+[*]
+indent_style = tab
+indent_size = 4
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.md]
+trim_trailing_whitespace = false
+
+[*.sh]
+indent_style = space
+indent_size = 4