fix: skip rate limit timer for short blocks (≤10 min) — CLI handles internally

The rate limit auto-scheduler was creating timers for every hard block,
including short 5-minute throttles. This caused a death loop: agent hits
rate limit, timer set, agent exits, pipeline restarts before timer fires,
new agent dies instantly (Session: None) because API is still throttled.

Short rate limits are handled naturally by the CLI's internal wait. Only
schedule timers for long session-level blocks (>10 min) where the CLI
will exit and needs external restart.

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

server/src/chat/timer.rs

@@ -255,6 +255,18 @@ pub fn spawn_rate_limit_auto_scheduler(
                     agent_name,
                     reset_at,
                 }) => {
+                    // Skip short rate limits (≤10 min) — the CLI handles
+                    // these internally.  Only schedule timers for long
+                    // session-level blocks where the CLI will exit.
+                    let until_reset = reset_at.signed_duration_since(chrono::Utc::now());
+                    if until_reset.num_minutes() <= 10 {
+                        crate::slog!(
+                            "[timer] Skipping short rate limit for {story_id} \
+                             ({} min); CLI will handle internally",
+                            until_reset.num_minutes()
+                        );
+                        continue;
+                    }
                     crate::slog!(
                         "[timer] Auto-scheduling timer for story {story_id} \
                          (agent {agent_name}) to resume at {reset_at}"