fix: Fix row limit detection for multiline LIMIT clauses

[Anjanna]

Description

Summary

Fixes #1592

Fixes pgcli's row limit detection when a SQL query contains a LIMIT clause followed by a newline.

Previously, pgcli checked for LIMIT using a string search for "limit ", so queries like this were not recognized as already limited:

SELECT *
FROM foo
LIMIT
    10000;

As a result, pgcli could incorrectly apply its configured row limit and show the row-limit warning. This change uses parsed SQL tokens to detect real LIMIT keywords, including multiline and tab-separated formatting, while ignoring LIMIT inside strings or comments.

Checklist

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