Add safe query-type grouping for Recent results from deterministic facts

[alexandrefimov]

Recent results need query-type grouping, but only after the product has deterministic classifier facts that can explain supported, unknown, and unsupported shapes without reading or rendering raw SQL.

Scope:

• derive query-type labels from analyzer-owned structured facts only;
• keep unknown and unsupported types explicit;
• keep grouping raw-free across Recent results, Details links, workload summaries, and any exported/trusted text;
• do not expose SQL text, identifiers, predicates, literals, local paths, raw artifacts, or model/runtime internals;
• do not infer query type from free-form model text or browser-visible sanitized strings.

Acceptance criteria:

• Analyzer exposes an allowlisted query-type classification contract with explicit unknown/unsupported states.
• Recent result grouping uses only that contract and degrades safely when the fact is absent.
• Browser/display safety tests prove that raw SQL, identifiers, predicates, and literals do not appear in the new surface.
• Fixtures cover at least one supported type, one unknown shape, and one unsupported shape.
• Documentation/changelog drift is checked and updated if the visible workflow changes.

Maintainer notes:

This is maintainer-owned because it touches analyzer facts, product routing, browser safety, and workload grouping semantics. Do not open a PR without agreeing on the classifier contract first.