feat: expose granular trace event targets

[beinan]

Summary

• Add granular tracing targets for Lance event categories under lance::events::....
• Preserve the original tracing target in Python log passthrough so LANCE_LOG can filter individual event types directly.
• Document the new event targets and add Python regression coverage for target-specific log filtering.

Testing

• PATH=/Users/beinan/.rustup/toolchains/1.94.0-aarch64-apple-darwin/bin:$PATH cargo fmt --all -- --check
• git diff --check
• PATH=/Users/beinan/.rustup/toolchains/1.94.0-aarch64-apple-darwin/bin:$PATH cargo check -p lance-core -p lance-io -p lance-index -p lance -p lance-datafusion
• PATH=/Users/beinan/.rustup/toolchains/1.94.0-aarch64-apple-darwin/bin:$PATH cargo check --manifest-path python/Cargo.toml
• uv sync --python 3.12 --no-install-project
• .venv/bin/maturin develop --uv -v
• uv run --no-sync --python 3.12 pytest -q python/tests/test_log.py::test_lance_log_filters_trace_event_targets python/tests/test_tracing.py::test_tracing_callback
• uv run --no-sync --python 3.12 ruff format --check python/tests/test_log.py python/tests/test_tracing.py
• uv run --no-sync --python 3.12 ruff check python/tests/test_log.py python/tests/test_tracing.py

[codecov]

Codecov Report

❌ Patch coverage is 90.00000% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
rust/lance/src/index.rs	0.00%	1 Missing ⚠️

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[claude]

Claude Code Review

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