test(kanban): cover task_age safe-int guards + AUTHOR_MAP entry

Follow-up to the previous commit's safe-int task_age fix.

The original PR shipped without test coverage. This commit adds:

- test_safe_int_accepts_int_and_int_string — sanity for the well-typed
  path so the helper itself can't quietly start swallowing valid values.
- test_safe_int_returns_none_on_corrupt_inputs — the failure modes
  (None, '%s', 'abc', '', '1.5', random objects). Covers both the
  ValueError and TypeError catch branches.
- test_task_age_handles_corrupt_created_at — the headline regression:
  a task with created_at='%s' used to raise ValueError and turn
  GET /api/plugins/kanban/board into a 500.
- test_task_age_handles_corrupt_started_and_completed — confirms the
  safe-int treatment is consistent across all three timestamp fields.
- test_task_age_well_formed_task — regression that the safe path
  doesn't change observable output for normal data.
- test_task_dict_survives_corrupt_created_at — defense in depth.
  Writes a corrupt row directly via SQL, reads it back through the
  ORM, and confirms task_age + the surrounding plugin_api guard
  degrade gracefully instead of crashing.

Also adds the AUTHOR_MAP entry for the contributor's GitHub-noreply
email so release notes credit @baocin (the commit was authored locally
as `aoi <aoi@hino.local>` — re-attributed during salvage to the
github noreply form).

scripts/release.py

@@ -712,6 +712,7 @@ AUTHOR_MAP = {
     "guoyu801@gmail.com": "li0near",
     "ty@tmrtn.com": "tymrtn",
     "elitovsky@zenproject.net": "kallidean",
+    "5463986+baocin@users.noreply.github.com": "baocin",
     "23434080+sicnuyudidi@users.noreply.github.com": "sicnuyudidi",
     "haimu0x0@proton.me": "haimu0x",
     "abdelmajidnidnasser1@gmail.com": "NIDNASSER-Abdelmajid",