fix(repair): wait out transient SQLite contention

[igorls]

What changed

• Give sqlite_integrity_errors() an explicit 15-second SQLite busy timeout.
• Add a deterministic regression test that verifies the connection contract without a multi-second sleep.

Why

PRAGMA quick_check previously inherited Python's five-second default timeout. A healthy palace with a longer-running batch writer could therefore return database is locked, which callers interpreted as SQLite corruption. Contention should get a bounded grace period; actual quick_check findings still fail exactly as before.

This is the clean replacement for the core fix in #1932. It deliberately excludes that branch's unrelated L1 and CLI commits and its seven-second test.

Local validation

• uv run pytest tests/test_repair.py -q — 92 passed
• uv run ruff check mempalace/repair.py tests/test_repair.py
• uv run ruff format --check mempalace/repair.py tests/test_repair.py
• Real SQLite smoke on this Mac: held BEGIN EXCLUSIVE from a peer connection for ~0.35s; sqlite_integrity_errors() waited and returned clean after the writer released.

Supersedes the intended repair-only portion of #1932.

[Copilot]

Pull request overview

This PR makes sqlite_integrity_errors() tolerant of routine transient SQLite writer contention by explicitly increasing the busy wait window to 15 seconds, preventing “database is locked” from being surfaced as apparent corruption during PRAGMA quick_check. It also adds a deterministic regression test that asserts the connection-timeout contract directly (avoiding a multi-second sleep-based lock test).

Changes:

• Add _SQLITE_INTEGRITY_BUSY_TIMEOUT_SECONDS = 15.0 and pass it via sqlite3.connect(..., timeout=...) for the PRAGMA quick_check connection.
• Add a regression test that monkeypatches sqlite3.connect to assert the uri=True + timeout=... connection arguments and the executed PRAGMA quick_check.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
mempalace/repair.py	Adds a bounded (15s) SQLite busy timeout to the quick_check connection used by sqlite_integrity_errors().
tests/test_repair.py	Adds a deterministic regression test asserting the new connection contract without introducing a real-time sleep.

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