feat(plugins): add git-ai-commit, diffview, and reorganize keymaps

- Add AI-powered commit message generation with git-ai-commit plugin.
- Add diffview for side-by-side git diffs.
- Reorganize telescope keymaps (<leader><leader> for live_grep, <leader>/ for find_files).
- Update lazy.nvim imports to include plugins.extras.
- Add mago.nvim for PHP support.
- Update AI plugin with model configuration.

lua/plugins/mago.lua

@@ -0,0 +1,5 @@
+return {
+  'calvinludwig/mago.nvim',
+  ft = 'php',
+  opts = {},
+}