refactor(kon): remove LLM command stubs — will be rewritten with llama-cpp-rs in Phase 3

- Remove 8 LLM command registrations from invoke_handler macro
- Delete commands/llm.rs stub file
- Remove pub mod llm from commands/mod.rs
- Build passes cleanly with cargo clippy

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src-tauri/src/commands/mod.rs

@@ -1,7 +1,6 @@
 pub mod audio;
 pub mod clipboard;
 pub mod hardware;
-pub mod llm;
 pub mod models;
 pub mod transcription;
 pub mod windows;