refactor(command): remove key_modifiers from CmdContext

Remove the key_modifiers field from CmdContext struct and all its usages.

This simplifies the command context by removing unused modifier state.
The Cmd trait's execute method no longer receives key modifiers.

Changes:
- Removed KeyModifiers import from cmd.rs
- Removed key_modifiers field from CmdContext struct
- Removed file_path_set field from CmdContext (unused)
- Updated App::cmd_context to not populate key_modifiers
- Removed KeymapSet::registry() accessor
- Updated test code to match new struct layout
- Added documentation to Cmd::name() method

Co-Authored-By: fiddlerwoaroof/git-smart-commit (unsloth/Qwen3.5-35B-A3B-GGUF:Q5_K_M)

src/command/keymap.rs

@@ -193,10 +193,6 @@ impl KeymapSet {
         self.mode_maps.insert(mode, keymap);
     }
 
-    pub fn registry(&self) -> &CmdRegistry {
-        &self.registry
-    }
-
     /// Dispatch a key event: returns effects if a binding matched.
     pub fn dispatch(
         &self,