fix(custodian-sweep): raise per-repo timeout from 120s to 180s

[ProtocolWarden]

Summary

• OC custodian-audit takes ~94s under light load but exceeds 120s when the sweep runs parallel jobs
• The 120s timeout caused the sweep to emit custodian-audit timed out (>120s) for OperationsCenter every cycle, even though the audit reports 0 findings
• Raising default to 180s eliminates false-positive timeout errors for OC without affecting other repos

Root cause

OC is the largest managed repo; its audit is CPU-bound across many detectors. Under parallel sweep load, scheduling contention pushes it past 120s. The fix in PR #297 (service.py C29 exclusion) reduced audit time but not enough to reliably stay under 120s.

Test plan

• tests/test_custodian_sweep.py (11/11 pass — imports _DEFAULT_TIMEOUT_SECONDS directly, no hardcoded value)
• tests/unit/er000_phase0_golden/ (15/15 pass)
• OC pre-push audit: 0 findings (confirmed clean)

🤖 Generated with Claude Code

[ProtocolWarden]

Needs human attention (reason=rebase_conflict). Left open — not merged (unresolved) and not closed (work preserved).

Auto-rebase onto the base branch hit a real code conflict (beyond the union-merged journal). Manual rebase required.

[ProtocolWarden]

Needs human attention (reason=rebase_conflict). Left open — not merged (unresolved) and not closed (work preserved).

Auto-rebase onto the base branch hit a real code conflict (beyond the union-merged journal). Manual rebase required.

[ProtocolWarden]

Resolved: new push — automated review resumed

Needs human attention (reason=rebase_conflict). Left open — not merged (unresolved) and not closed (work preserved).

Auto-rebase onto the base branch hit a real code conflict (beyond the union-merged journal). Manual rebase required.