PromQL: punted queries not enforced at runtime, can be silently served via capability-matching #528

Scope: streaming_engine=precompute, PromQL.

The planner punts low-sample-count queries (asap-planner-rs/src/planner/promql.rs:182-217, should_be_performant) and omits them from query_configs/aggregation_configs (asap-planner-rs/src/promql/generator.rs:72-91). Nothing downstream enforces this — asap-query-engine's query tracker only logs punted_queries.len().

If a punted query shares metric/statistic/grouping-labels/spatial-filter with an accepted sibling query whose aggregation window size evenly divides it, the engine's capability-matching fallback (build_query_execution_context_promql, asap-query-engine/src/engines/simple_engine/promql.rs:1025-1056) serves the punted query anyway.

Repro: planned two quantile_over_time(0.9, m[Xm]) variants — one punted (too few samples), one accepted with a compatible window. Confirmed the punted query has no query_config, but build_query_execution_context_promql on it still returns Some(...).