feat: Support PostgreSQL regular expression operators (~, ~*, !~, !~*)

[ajitpratap0]

Description

Add support for PostgreSQL's regular expression matching operators.

Operators Needed

• ~ - Case-sensitive regex match
• ~* - Case-insensitive regex match
• !~ - Case-sensitive regex non-match
• !~* - Case-insensitive regex non-match

Example SQL

SELECT * FROM users WHERE name ~ '^J.*';
SELECT * FROM products WHERE description ~* 'sale|discount';
SELECT * FROM logs WHERE message !~ 'DEBUG';
SELECT * FROM emails WHERE subject !~* 'spam';

Current Behavior

These regex operators are not recognized.

Expected Behavior

Parser should tokenize and parse these as binary comparison operators.

Priority

Medium - useful for text pattern matching in PostgreSQL

Implementation Notes

• Add token types: TokenTypeTilde, TokenTypeTildeAsterisk, TokenTypeNotTilde, TokenTypeNotTildeAsterisk
• Handle these as binary operators in expression parsing