[codex] ROY-25: For Multi-project polling control, we only need one config for it.

[0xroylee]

Linear issue: ROY-25

This PR was created by the PIV Loop workflow.

Includes:

• plan + implement session output
• separate review/testing session

[0xroylee]

PIV loop review for ROY-25

Result: PASS

Token usage: input 81814, output 1058, total 82872

Reviewed the branch diff against origin/main...HEAD for ROY-25, focusing on the polling refactor from per-project to root-level config, and found no functional regressions in configuration resolution, workflow polling behavior, or related tests; all required quality gates passed successfully on May 6, 2026 (bun run check, bun run typecheck, and bun test with 46/46 tests passing), and coverage was updated to validate rejection of project-level polling overrides plus root polling env behavior.

No bugs found.