v1.9.2 - SQLite Timestamp Fix

[DredBaron]

What changed and why

All database migrations used PostgreSQL-only SQL now() as the default value for several timestamp columns, which caused every write to those columns to fail with unknown function: now() on SQLite-backed installs. This fix corrects the migrations to use SQLAlchemy's dialect-aware func.now() instead, and adds a new migration that repairs the broken defaults on existing SQLite databases automatically on upgrade.

Type of change

• Bug fix
• New feature
• Refactor / chore
• Documentation

Testing

• pytest passes with no warnings
  1 pre-existing xfail (documented SQLite downgrade gap, not introduced by this change) and 1 pre-existing warning (httpx/TestClient deprecation, unrelated). All other tests pass, test suite is being updated to take these into account.
• npm run lint passes (frontend changes)
  No frontend changes have been made this release.

Manually ran and passed database migrations to ensure no data loss on error correction.

Related issues

Closes #45

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