Fix build warnings across workspace

- Remove redundant token fields from StreamEvent::Finished (data
  already delivered via Usage event)
- Remove dead hotkey_adjust_sampling, MAX_HISTORY, now()
- Fix unused variable warnings (delta, log)
- Suppress deserialization-only field warnings (jsonrpc, role)
- Make start_stream/chat_completion_stream_temp pub(crate)
- Remove unnecessary pub(crate) re-export of internal types

Remaining warnings are TODO items: SkipIndex (scoring not wired),
notify (MCP notifications not wired).

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

src/user/mod.rs

@@ -263,17 +263,6 @@ fn hotkey_cycle_autonomy(mind: &crate::mind::Mind) {
     }
 }
 
-fn hotkey_adjust_sampling(mind: &crate::mind::Mind, param: usize, delta: f32) {
-    if let Ok(mut ag) = mind.agent.try_lock() {
-        match param {
-            0 => ag.temperature = (ag.temperature + delta).clamp(0.0, 2.0),
-            1 => ag.top_p = (ag.top_p + delta).clamp(0.0, 1.0),
-            2 => ag.top_k = (ag.top_k as f32 + delta).max(0.0) as u32,
-            _ => {}
-        }
-    }
-}
-
 /// Returns true if this is an event the main loop handles (F-keys, Ctrl combos, resize).
 fn is_global_event(event: &ratatui::crossterm::event::Event) -> bool {
     use ratatui::crossterm::event::{Event, KeyCode, KeyModifiers, KeyEventKind};