fix(dashboard): paginate CEO dashboard ticket fetch to respect API cap

The CEO dashboard requested /api/tickets?page_size=500, but the API caps
page_size at 200 (le=200 in app/routers/tickets.py), so the request
returned 422 and every KPI/chart rendered zeros.

- ceo.html: fetch all tickets by looping pages of page_size=200 until
  total items are collected (with a safety bound), keeping KPIs accurate
  as volume grows past 200.
- tests: add test suite anchoring the pagination contract — page_size=500
  returns 422, page_size=200 returns items/total/page/page_size, and a
  page loop collects every ticket without duplicates.
- pyproject: enable pytest-asyncio auto mode and tests/ discovery.
- .gitignore: un-ignore committed tests/test_*.py.

.gitignore

@@ -6,6 +6,7 @@ __pycache__/
 .venv/
 uploads/
 test_*.py
+!tests/test_*.py
 venv/
 *.egg-info/
 dist/