[ZhuchkaTriplesix]

Summary

isAllowedPostgresSelectQuery split the script with maskSqlLiteralsForLimitScan followed by a hand-written _maskPostgresComments. The first pass already blanks comments, strings, quoted identifiers and dollar quotes, so the second pass produced a third copy of the text and never changed it. It is deleted (~35 lines), and the semicolon scan uses codeUnitAt instead of one-character strings.

Why not SqlStatementSplitter.spans (the issue's proposal)

This function is the gate that keeps writes out of the Table Browser, so it has to split where PostgreSQL splits. SqlStatementSplitter follows MySQL-style lexing that PostgreSQL does not:

Input	PostgreSQL	SqlStatementSplitter
SELECT 'a\'; DELETE FROM t; --'	literal 'a\' ends at the second quote, then DELETE runs	\' is an escape: one SELECT statement, gate would allow the DELETE
SELECT 1 ` 2; DELETE FROM t; SELECT 1 ` 3	backtick is an operator character	backtick quotes: one statement
SELECT 1 /* a /* b */ ; DELETE ...; */	nested comment, one SELECT	comment ends at the first */: rejected

So the existing masking is kept (it already follows PostgreSQL), and tests pin these cases.

Tests (not run locally; CI will)

New test in postgres_table_utils_test.dart covering the three rows above plus semicolons in a quoted identifier and in a dollar quote.

Closes #1517