feat: integrate profile completeness check into captcha verification

[rezhajulio]

Summary

Combines captcha verification with a mandatory profile completeness check (photo + username) before unrestricting new members.

Changes

Captcha + Profile Check Integration

• When a user clicks the captcha button, their profile is checked first
• If incomplete, an alert shows what's missing (photo, username, or both) — user can retry
• Timeout job is preserved until profile check passes, preventing users from getting stuck
• Welcome message updated to inform users about profile requirements upfront

Handler Hardening

• Added parse guard for malformed callback data (ValueError/IndexError)
• Moved timeout job cancellation after successful unrestrict + DB cleanup (fixes bug where failed unrestrict would leave user stuck with no timeout)
• Wrapped DB finalization in try/except to prevent unanswered callbacks

Test Improvements

• Replaced fragile AsyncMock(is_complete=...) with real ProfileCheckResult dataclass in all mocks
• Added tests: malformed callback data, unrestrict failure preserving timeout, incomplete profile (single/both missing), profile check API exception

Flow

1. User joins → restricted → captcha message sent
2. User clicks button → profile checked
3. If incomplete → alert with missing items, timeout stays active
4. If complete → unrestrict → cleanup DB → cancel timeout → success message

Tests: 555 passed, ~99.9% coverage