fix: pass request_overrides to background review and curator agents

[TurgutKural]

Bug

Background review and curator agents were not inheriting request_overrides from the parent agent or the resolved runtime provider. This caused provider-specific extra_body fields (like store: false for custom providers) to be missing from their LLM API calls.

Reproduction: Configure a custom provider with extra_body: store: false (e.g. pioneer provider). Regular chat completions send store: false correctly, but background review (skill/memory updates) and curator calls do not — the provider stores these requests when it shouldn't.

Fix

• agent/background_review.py: The background review agent now inherits request_overrides from the parent agent via getattr(agent, "request_overrides", None).
• agent/curator.py: The curator agent now extracts request_overrides from the resolved runtime provider (_rp.get("request_overrides")), matching the behavior of the main agent initialization path.

Root Cause

Both agent creation sites (background_review.py:648 and curator.py:1878) called AIAgent(...) without passing request_overrides. Since init_agent defaults request_overrides to {}, the provider's extra_body config was silently dropped for these auxiliary LLM calls.

Testing

• Both files pass py_compile syntax check
• The fix is minimal (4 lines added) and follows the existing pattern used in cli_commands_mixin.py which already passes request_overrides to its background agent