feat(treesitter): add diff, gitcommit and missing parsers

diff and gitcommit cover commit buffers and diff output. cpp, kotlin and
nix were formatted by conform with no parser installed.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.md

@@ -37,6 +37,10 @@ Leader is `<Space>`. NvChad's defaults apply except where overridden in
 | `<C-f>` | Live grep |
 | `<C-g>` | Git status |
 | `<leader>b` | Buffers |
+| `<leader>fo` | Old files |
+| `<leader>fz` | Find in current buffer |
+| `<leader>fh` | Help tags |
+| `<leader>ma` | Marks |
 | `<leader>y` / `<leader>Y` | Yazi at current file / cwd |
 
 ### LSP
@@ -63,6 +67,13 @@ Leader is `<Space>`. NvChad's defaults apply except where overridden in
 | Key | Action |
 | --- | --- |
 | `<leader>g` | Neogit |
+| `<leader>cm` | Git commits |
+| `]c` / `[c` | Next / previous hunk |
+| `<leader>hp` | Preview hunk |
+| `<leader>hr` | Reset hunk |
+| `<leader>hb` | Blame line |
+| `<leader>hd` | Diff buffer against index |
+| `co` / `ct` / `cb` / `c0` | Resolve conflict: ours / theirs / both / none |
 
 ### Editing
 

lua/plugins/treesitter.lua

@@ -16,9 +16,14 @@ return {
         "vim",
         "lua",
         "vimdoc",
+        "diff",
+        "gitcommit",
         "html",
         "css",
         "c_sharp",
+        "cpp",
+        "kotlin",
+        "nix",
         "rust",
         "regex",
         "javascript",