add update_inner_state tool, life loop with tools, timeout protection

- update_inner_state: LLM can update its own persistent inner state
- inner_state injected into chat loop system prompt (read-only)
- Life Loop now uses run_openai_with_tools (full tool access)
- Life Loop LLM calls wrapped in 120s tokio::time::timeout
- All reqwest clients: 120s timeout (whisper: 60s)
- doc/life.md: life loop architecture design doc
- todo.md: removed completed items

src/state.rs

@@ -248,7 +248,6 @@ impl AppState {
             .unwrap_or_default()
     }
 
-    #[allow(dead_code)] // used by life loop tools (coming soon)
     pub async fn set_inner_state(&self, content: &str) {
         let db = self.db.lock().await;
         let _ = db.execute(