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>

channels/irc/src/main.rs

@@ -29,7 +29,6 @@ use poc_memory::thalamus::channel_log;
 
 // ── Constants ──────────────────────────────────────────────────
 
-const MAX_HISTORY: usize = 1000;
 const RECONNECT_BASE_SECS: u64 = 5;
 const RECONNECT_MAX_SECS: u64 = 300;
 const PING_INTERVAL_SECS: u64 = 120;
@@ -236,12 +235,6 @@ fn append_log(target: &str, nick: &str, text: &str) {
     channel_log::append_disk_log(&log_dir(), target, nick, text);
 }
 
-fn now() -> f64 {
-    std::time::SystemTime::now()
-        .duration_since(std::time::UNIX_EPOCH)
-        .unwrap_or_default()
-        .as_secs_f64()
-}
 
 // ── TLS ────────────────────────────────────────────────────────