ttl-keyed-json-cache-lenient-decode

A small keyed cache for values that drift — each entry carries the moment it was fetched and answers an isStale check against a time-to-live constant, the whole map is stored as one JSON string in key-value preferences, and decoding is lenient plus wrapped so a schema change degrades to a cache miss instead of destroying every entry. Use when caching resolved covers, lookups or per-key results without a database…