WEST COAST PEST - OPTION B - STEP 4

Purpose
- Fix worksite resolution for users who already have valid assignments.
- Fix PDO placeholder issues in helper queries.
- Add safe fallback order: primary assignment -> active assignment -> recent history -> first company worksite.

Overwrite these files into /public_html/pest/api/
- helpers.php
- my-worksite.php

Then hard refresh /pest/attendance/ and test:
1. login
2. confirm worksite now shows
3. clock in
