fix(clickhouse): refuse values with no SQL literal instead of writing String(value) - #36

🟢 Confidence 10/10 · safe to merge
Only docs changed since the last review; the refusal path is pinned by seven typed tests and the one open wording defect remains.
_{1 note · tests covered · risk medium}

The toFragment fallback now fails compilation with InvalidLiteral instead of writing String(value) as SQL, and the guide documents the refused values. The new behavior is tested and safe; only the error wording in describeUntyped remains wrong.

Still open from earlier reviews

• 🔵 Note · F1 · describeUntyped says "a object" instead of "an object" · src/ch/expr.ts:325

_{32d91da · Updated on every push. Reply "won't fix" to dismiss a finding, or mention @maple-review-bot to ask about one.}