Add resilience to DuckDB read lock acquisition

[erikdarlingdata]

Summary

• Catches LockRecursionException in AcquireReadLock() and returns a no-op disposable instead of throwing
• If an unhandled exception (like the tray tooltip crash in System tray custom tooltip causes unhandled WPF crash #422) leaks a read lock on the UI thread, the lock is permanently poisoned — every subsequent EnterReadLock() throws because the thread already owns one
• Since the thread already has read protection, it's safe to proceed without acquiring another lock
• This makes the lock self-healing: operations recover gracefully rather than failing forever until restart

Files changed

File	Change
Lite/Database/DuckDbInitializer.cs	Add LockRecursionException catch in AcquireReadLock(), add NoOpDisposable class

Fixes #423

Test plan

• Lite builds clean (0 warnings, 0 errors)
• Normal operation: overview tab loads server summaries
• Resilience: if tray tooltip crash leaks the lock, overview continues working

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