fix: restore SecuScan CI baseline

[saurabhhhcodes]

Summary

• fix the workflow scheduler lint failure by acquiring the database handle before resolving target policy
• update stale execution-context expectations in ToolConfig and Workflows tests
• align the timeout test with the current validated max value emitted by ToolConfig

Root Cause

The current CI baseline was failing on main-based PRs because:

• backend/secuscan/workflows.py referenced db inside _run_workflow() without defining it
• frontend tests still expected the pre-execution-context payload shape
• the timeout test expected the older server-limit clamp value

Validation

• python3 -m ruff check backend testing/backend
• npm test -- --run testing/unit/pages/ToolConfigDynamic.test.tsx testing/unit/pages/ToolConfigTimeout.test.tsx testing/unit/pages/Workflows.test.tsx
• npm test
• git diff --check

Impact

Restores the CI baseline for unrelated frontend/backend PRs, including the hook coverage PR that exposed these existing failures.