feat: soft-split SQL statements at 2+ blank lines when ; is missing

[Blankll]

Problem

When a user forgets a ; between two SQL statements, the entire text is sent as one query and PostgreSQL returns a syntax error like:

syntax error at or near "SELECT"

This is a common UX friction — users often write multiple queries separated by blank lines without remembering the trailing ;.

Solution

Added splitRangesAtBlankLines() that runs as a post-processing step after the standard ;-based split. For each statement range, it scans for 2+ consecutive blank lines followed by a SQL keyword. When found, the range is split at that point.

Split keywords: SELECT, CREATE, ALTER, DROP, INSERT, UPDATE, DELETE, TRUNCATE, GRANT, REVOKE, EXPLAIN, SHOW, DESCRIBE, USE, SET, CALL, EXEC/EXECUTE, BEGIN, COMMIT, ROLLBACK, DECLARE, ANALYZE, VACUUM, PRAGMA, REFRESH, COPY, WITH, MERGE, REPLACE

Safety: Requires 2+ blank lines (not 1) to avoid false positives — a single blank line within a multi-line statement won't split it.

Example

SELECT * FROM users;
-- forget ;
SELECT * FROM orders;

→ Still one statement (1 blank line, safe)

SELECT * FROM users;


SELECT * FROM orders;

→ Split into 2 statements (2 blank lines + SELECT keyword)

Verification

• 452 tests pass (no regressions)
• 6 new test cases covering multi-statement, single-blank (no split), mixed ;/blank-line, and position correctness
• Lint clean