feat(conductor): task state machine — TIMED_OUT state and retriable steps

- Add 'timed_out' to flow_runs/flow_steps CHECK constraints
- Add retry_count and max_retries columns to flow_steps
- Add timeout detection in advanceInner loop (configurable FLOW_STEP_TIMEOUT_MS)
- Add retriable logic: re-dispatch on timeout if maxRetries > 0 and retryCount < maxRetries
- Add isRetriable() + shouldRetry() pure decision functions
- Add timed_out handling to reconcileResumeStep and reconcileRun
- Add 'timed_out' to ws-frames enum, publishStep status type

apps/coder/src/config.ts

@@ -52,6 +52,9 @@ const ConfigSchema = z.object({
   ORPHAN_WORKTREE_GRACE_MS: z.coerce.number().int().positive().default(3_600_000),
   DEEPSEEK_API_KEY: z.string().optional(),
   DEEPSEEK_BASE_URL: z.string().url().default('https://api.deepseek.com'),
+  // v2.9.x: flow step timeout (default 5 min). When a 'running' step exceeds
+  // this duration, it is marked 'timed_out' and may be retried.
+  FLOW_STEP_TIMEOUT_MS: z.coerce.number().int().positive().default(300_000),
 });
 
 export type Config = z.infer<typeof ConfigSchema>;