fix(core): auto-recover corrupted sqlite database on startup

[leecoder]

Issue for this PR

Closes #37821

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

When the SQLite database file is corrupted, opencode crashes on startup with database disk image is malformed or file is not a database. This happened to me after a power loss corrupted the WAL file.

The fix wraps DB initialization with Layer.catchCause. If the init fails with a corruption-related SQLite error, it:

1. Renames the corrupted .db, -wal, -shm files with a .corrupt-<timestamp> suffix
2. Retries initialization with a fresh database
3. Logs a warning so the user knows recovery happened

The detection uses error message matching (file is not a database / database disk image is malformed) rather than header-only inspection, so it catches both header corruption and internal page corruption.

If the backup rename itself fails (permissions, file lock), it logs a distinct warning instead of silently claiming success.

How did you verify your code works?

• Added a test in database-migration.test.ts that writes a file with valid SQLite header but corrupted internal pages, then verifies recovery creates a working database and the .corrupt-* backup exists
• Manual smoke test with a fully corrupted file confirmed the warning log and fresh DB creation
• bun typecheck passes for both packages/core and packages/opencode

Screenshots / recordings

N/A - not a UI change

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR