feat(postgres): add configurable pg_trgm extension support

[benfdking]

Summary

• Add support for PostgreSQL pg_trgm extension operators (%, <%, %>, <->, etc.)
• Make pg_trgm support opt-in via dialect configuration
• Add test infrastructure for per-folder dialect config in test fixtures

To enable pg_trgm operators, add to your .sqruff config:

[sqruff:dialect:postgres]
pg_trgm = true

See: https://www.postgresql.org/docs/current/pgtrgm.html

Fixes #1180

Based on work from #1186 by @lu-zero and @gvozdvmozgu

Test plan

• bazel test //... passes
• pg_trgm operators parse correctly when enabled
• pg_trgm operators don't interfere when disabled

🤖 Generated with Claude Code

[github-actions]

Benchmark for 4f8f330

Click to view benchmark

Test	Base	PR	%
DepthMap::from_parent	52.4±1.69µs	52.3±0.60µs	-0.19%
fix_complex_query	12.3±0.07ms	12.3±0.06ms	0.00%
fix_superlong	156.5±3.06ms	174.5±4.71ms	+11.50%
parse_complex_query	4.2±0.05µs	4.2±0.06µs	0.00%
parse_expression_recursion	7.1±0.07µs	7.5±0.12µs	+5.63%
parse_simple_query	1035.1±19.29ns	1058.0±27.35ns	+2.21%

[codspeed-hq]

Merging this PR will improve performance by 18.84%

⚡ 2 improved benchmarks
✅ 4 untouched benchmarks
⏩ 6 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	WallTime	parse_complex_query	16.7 µs	14.9 µs	+11.99%
⚡	WallTime	parse_expression_recursion	27.7 µs	23.3 µs	+18.84%

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_{Comparing feat/postgres-pgtrgm-config (f2f29e7) with main (dcda784)²}

Footnotes

1. 6 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on main (ac70e23) during the generation of this report, so dcda784 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩