Pre-migration cleanup: remove stale configs, fix portability issues

- Remove dead tracked files: .vimrc, .vim/ (using Neovim now), .config/oni2/
  (Onivim 2 discontinued), .config/iterm2/AppSupport, .config/kitty/theme.conf
  (generated at runtime by apply_theme.sh)
- Track .config/nvim/lazy-lock.json for reproducible plugin versions
- Fix .gitconfig: update core.excludesfile to use ~ instead of hardcoded path;
  create .gitignore_global with common OS/editor patterns
- Commit .gitconfig [filter "lfs"] section that was left unstaged
- Make launchd plist portable: use __HOME__ placeholder with sed substitution
  in install.sh so it works regardless of username on new machine
- Update Brewfile: add jq, karabiner-elements, raycast (installed but missing)
- Clean up .gitignore: remove stale oni2/jgit/spacebar entries
- Update CI to also lint scripts/apply_theme.sh (matching local check.sh)

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: folone

.config/iterm2/AppSupport

@@ -0,0 +1,13 @@
+{
+  "LuaSnip": { "branch": "master", "commit": "3732756842a2f7e0e76a7b0487e9692072857277" },
+  "catppuccin": { "branch": "main", "commit": "234fc048de931a0e42ebcad675bf6559d75e23df" },
+  "cmp-nvim-lsp": { "branch": "main", "commit": "bd5a7d6db125d4654b50eeae9f5217f24bb22fd3" },
+  "gitsigns.nvim": { "branch": "main", "commit": "20ad4419564d6e22b189f6738116b38871082332" },
+  "lazy.nvim": { "branch": "main", "commit": "85c7ff3711b730b4030d03144f6db6375044ae82" },
+  "lualine.nvim": { "branch": "master", "commit": "3946f0122255bc377d14a59b27b609fb3ab25768" },
+  "nvim-cmp": { "branch": "main", "commit": "106c4bcc053a5da783bf4a9d907b6f22485c2ea0" },
+  "nvim-lspconfig": { "branch": "master", "commit": "c8503e63c6afab3ed34b49865a4a4edbb1ebf4a8" },
+  "nvim-treesitter": { "branch": "master", "commit": "42fc28ba918343ebfd5565147a42a26580579482" },
+  "plenary.nvim": { "branch": "master", "commit": "b9fd5226c2f76c951fc8ed5923d85e4de065e509" },
+  "telescope.nvim": { "branch": "master", "commit": "6312868392331c9c0f22725041f1ec2bef57c751" }
+}