fix(oraclemcp-guard): make analyze_batch keyword tally quote_style-aware [oracle-qm3q.3]

A double-quoted identifier ("BEGIN"/"END" — a column name, not a PL/SQL keyword)
was uppercased and matched as a structural keyword, moving the BEGIN/END depth
counter. So `SELECT "BEGIN" FROM dual; END;` inflated depth by 1, the stray
top-level END netted back to 0, and the batch was downgraded Forbidden→Guarded —
defeating the fail-closed desync law.

Fix: only bare words (w.quote_style.is_none()) are considered structural keywords;
delimited identifiers are treated as content. Regression test added.
59 guard lib tests green; clippy -D warnings clean; boundary lint OK.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: Durak