feat: add pretty fixtures for quoting and formatting behaviors

[pyramation]

feat: add pretty fixtures for quoting and formatting behaviors

Summary

Adds test fixtures to document deparser behavior for several SQL formatting scenarios observed in downstream repos:

Quoting fixtures (quoting.sql):

• Reserved keyword function names (float, interval, boolean) that require quoting
• pg_catalog."substring" with quoted identifier
• Tests both unquoted input forms and quoted canonical forms to verify the deparser correctly quotes reserved keywords

Formatting fixtures (formatting.sql):

• EXPLAIN with/without COSTS OFF optional keyword
• Boolean literal formatting ('t'::boolean cast vs TRUE literal)
• Function parameter modes (IN, OUT, INOUT) with parenthesization

Review & Testing Checklist for Human

• Verify quoting behavior: Check that snapshots show faker.float (unquoted input) deparsing to faker."float" (quoted output) - this is the key transformation being documented
• Verify boolean formatting: The snapshots show 't'::boolean becomes CAST('t' AS boolean) rather than TRUE - confirm this matches expected deparser behavior (differs from original diff which showed TRUE)
• SUBSTRING limitation: Note that SUBSTRING(value FROM 'pattern') SQL syntax was excluded because it cannot round-trip (different AST representation) - only the canonical pg_catalog."substring"(value, 'pattern') form is tested

Test plan:

cd packages/deparser
pnpm test -- quoting-pretty.test.ts
pnpm test -- formatting-pretty.test.ts

Notes

• Pre-existing test failures (12 kitchen-sink tests) and ESLint configuration issues are unrelated to this PR
• Link to Devin run: https://app.devin.ai/sessions/019c4a70e9164830aef1f807aad33e1d
• Requested by: Dan Lynch (@pyramation)

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