Debug Chalk query plan cache misses

Chalk caches a compiled query plan the first time it plans a query, keyed by a normalized BatchQuery. A cache miss forces the engine to replan on the hot path, which is slow. Misses are expected the first time a query shape is seen; they are a problem when a query that "looks identical" to a previous one keeps missing — that means some field in the request is varying between calls.

This skill: (1) finds misses in the logs, and (2) diffs the planned queries to identify exactly which field differs and forces the miss.

What the cache key actually is

The plan cache key wraps the entire normalized BatchQuery. The only normalization applied is that planner_options are resolved to their effective values — so leaving an option unset and setting it explicitly to its default produce the same key and will not cause a spurious miss.