feat: auto-detect formatter in post-edit hook (Biome/Prettier)

The post-edit-format hook was hardcoded to use Prettier. Projects using
Biome had their code reformatted with Prettier defaults (e.g. double
quotes overwriting single quotes).

Now the hook walks up from the edited file to find the project root,
then checks for config files:
- biome.json / biome.jsonc → runs Biome
- .prettierrc / prettier.config.* → runs Prettier
- Neither found → skips formatting silently

hooks/hooks.json

@@ -108,7 +108,7 @@
             "command": "node \"${CLAUDE_PLUGIN_ROOT}/scripts/hooks/post-edit-format.js\""
           }
         ],
-        "description": "Auto-format JS/TS files with Prettier after edits"
+        "description": "Auto-format JS/TS files after edits (auto-detects Biome or Prettier)"
       },
       {
         "matcher": "Edit",