stale cache can crash with _RuleFeatureIndex.bytes_prefix_index AttributeError

capa can crash when a stale rules cache (from older _RuleFeatureIndex schema) is loaded.
Current error: AttributeError: '_RuleFeatureIndex' object has no attribute 'bytes_prefix_index' during matching.
Expected behavior is cache invalidation/rebuild instead of runtime failure.
This impacts normal analysis and scripts that rely on cached rule loading.
Suggested fix: bump cache format (or equivalent invalidation) and handle schema mismatch as cache-miss.

Start by locating the cache-loading path and the _RuleFeatureIndex definition, then reproduce matching with a cache created from the older schema. Verify that the schema mismatch is treated as a cache miss and that the cache is invalidated or rebuilt without an AttributeError during normal analysis and cached rule loading.

Written by the indexing model from the issue text.