perf: defer database attachment for cached queries

[MichaReiser]

Defer database attachment until a tracked query takes a cold path, so cached top-level and nested queries avoid repeated TLS guard work.

Event callbacks, tracing, cancellation cleanup, and query execution still run with the database attached; mismatched databases continue to panic.

Testing: Passed the full test suite and all-features checks.

[netlify]

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[codspeed-hq]

Merging this PR will degrade performance by 7.77%

❌ 1 regressed benchmark
✅ 7 untouched benchmarks
🗄️ 34 archived benchmarks run¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	many_tracked_structs	8.5 µs	9.2 µs	-7.77%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing MichaReiser:optimize-query-attachment (57155d4) with master (dd0ae68)}

Footnotes

1. 34 benchmarks were run, but are now archived. If they were deleted in another branch, consider rebasing to remove them from the report. Instead if they were added back, click here to restore them. ↩

[MichaReiser]

huh