feat: advanced SQL syntax highlighting and expanded language support

[muk2]

Summary

Addresses the core syntax and language support goals from #4 to make pgrsql a power-user SQL editor with first-class support for modern PostgreSQL features:

• 200+ SQL keywords with comprehensive coverage for CTEs (WITH RECURSIVE), LATERAL joins, grouping sets (CUBE, ROLLUP, GROUPING SETS), transaction isolation levels, PL/pgSQL control flow (DECLARE, LOOP, RAISE, EXCEPTION), and DDL for functions, triggers, policies, extensions, and more
• 250+ SQL built-in functions recognized and highlighted in a distinct color (blue), covering:
  • Aggregate functions (ARRAY_AGG, STRING_AGG, PERCENTILE_CONT, JSON_AGG, etc.)
  • Window functions (ROW_NUMBER, RANK, DENSE_RANK, NTILE, LAG, LEAD, NTH_VALUE, CUME_DIST, etc.)
  • JSON/JSONB functions (JSONB_BUILD_OBJECT, JSONB_SET, JSONB_PATH_QUERY, ROW_TO_JSON, etc.)
  • Array functions (ARRAY_AGG, UNNEST, ARRAY_POSITION, CARDINALITY, etc.)
  • Date/time, string, numeric, full-text search, and system info functions
• 90+ SQL types including range types (INT4RANGE, TSTZRANGE), multirange, OID types (REGCLASS, REGTYPE), full-text search (TSVECTOR, TSQUERY), and pseudo-types
• Block comment support: /* */ comments are properly highlighted, including across multiple lines
• PostgreSQL operator highlighting: :: (type cast), -> / ->> (JSON), #> / #>> (JSON path), @> / <@ (containment), ?| / ?& (JSONB existence), || (concatenation)
• Escaped quote handling: '' inside string literals no longer breaks highlighting
• Schema-qualified names: Dot operator (.) styled as muted for clean schema.table readability

Syntax Color Scheme

Element	Color	Example
Keywords	Purple (bold)	SELECT, WITH RECURSIVE, LATERAL
Functions	Blue	ROW_NUMBER(), JSONB_BUILD_OBJECT()
Types	Yellow	TIMESTAMPTZ, JSONB, INT4RANGE
Strings	Green	'hello world'
Numbers	Orange	42, 3.14
Comments	Gray	-- comment, /* block */
Operators	Cyan	::, ->>, @>

Test plan

• Verify CTE keywords highlight (WITH, RECURSIVE, AS)
• Verify window function names highlight in blue (ROW_NUMBER, DENSE_RANK, LAG)
• Verify JSONB operators highlight (->, ->>, @>, #>>)
• Verify :: type cast operator highlights
• Verify block comments /* ... */ highlight across multiple lines
• Verify escaped quotes '' don't break string highlighting
• Verify SQL types like TSVECTOR, INT4RANGE, REGCLASS highlight in yellow
• Verify aggregate functions like ARRAY_AGG, STRING_AGG highlight in blue
• Verify PL/pgSQL keywords like DECLARE, RAISE, LOOP highlight

🤖 Generated with Claude Code