fix(query-engine): honor CountMinSketch sum/count subtype - #665

Summary

Fix CountMinSketch configuration semantics by validating subtype and honoring SUM versus COUNT weighting.

Changes

• Plain CountMinSketch requires aggregation_sub_type to be sum or count (case-insensitive, without trimming).
• Plain CMS sum uses sample values; count uses unit weights.
• CountMinSketchWithHeap requires aggregation_sub_type: topk.
• Heap CMS count_events, when present, must be a boolean; omitted remains the COUNT default.
• Invalid CMS configurations fail before workers and ingest sources start.
• Capability matching selects the matching plain-CMS subtype for SUM versus COUNT.
• The legacy MultipleSubpopulation path is unchanged.

Closes #505.

Tests

• cargo test -p asap_types --lib
• cargo test -p query_engine_rust --lib — 594 passed
• cargo fmt --all
• cargo check -p query_engine_rust
• cargo clippy -p query_engine_rust --all-targets -- -D warnings
• Pre-commit hooks passed.

Follow-ups

• fix(query-engine): reject sum-weighted heap CMS for COUNT matching #666 — reject sum-weighted heap CMS for ordinary COUNT matching
• fix(query-engine): make runtime plan reconfiguration consistent #669 — make runtime plan reconfiguration consistent
• refactor(asap-types): model aggregation kinds and subtypes with typed enums #670 — model aggregation kinds and subtypes with typed enums