fix(consolidation): release large objects between retry attempts to prevent RSS leak (#2273)

[handnewb]

Summary

When a consolidation LLM call fails repeatedly, the call_kwargs dict (containing the full system_prompt and user_content strings — potentially hundreds of KB of text) and the response object were kept in scope across the retry loop. With consolidation_max_attempts=5 and retry storms, repeated failures could accumulate hundreds of MB of unreclaimable memory, eventually causing OOM.

Changes

• Initialize call_kwargs and response as None before the retry loop
• Add finally block with explicit del to release references between retry attempts
• Use try/except NameError guards for safety (the variables may not be assigned if the exception occurs before their assignment line, though in practice this never happens)

Verification

• Successful consolidation path is unchanged (objects are naturally cleaned up on return)
• Failed retry path now releases references before the next attempt
• No functional change to consolidation logic

Closes #2273