fix: address 3 new CodeRabbit review comments

1. agent.py: Reset opposite retry counter when entering rate_limit or error
   status to prevent mixed events from inflating delays

2. rate_limit_utils.py: Fix parse_retry_after() regex to reject minute/hour
   units - patterns now require explicit "seconds"/"s" unit or end of string

3. test_rate_limit_utils.py: Add tests for "retry after 5 minutes" and other
   minute/hour variants to ensure they return None

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

agent.py

@@ -372,6 +372,8 @@ async def run_autonomous_agent(
 
         elif status == "rate_limit":
             # Smart rate limit handling with exponential backoff
+            # Reset error counter so mixed events don't inflate delays
+            error_retries = 0
             if response != "unknown":
                 try:
                     delay_seconds = clamp_retry_delay(int(response))
@@ -390,6 +392,8 @@ async def run_autonomous_agent(
 
         elif status == "error":
             # Non-rate-limit errors: linear backoff capped at 5 minutes
+            # Reset rate limit counter so mixed events don't inflate delays
+            rate_limit_retries = 0
             error_retries += 1
             delay_seconds = calculate_error_backoff(error_retries)
             print("\nSession encountered an error")