The dynamic-key sort throttle (3.3.0) used an inline ad-hoc cache
object with a Date.now() comparison. Pull it out into a clean
generic-purpose makeThrottledCache helper that takes the TTL and an
optional clock function so tests can drive time without sleeping.
Same dual-environment loader (CommonJS for tests, window global for
the renderer via index.html script tag) as queue-prune.
API: get(sig, input) / set(sig, input, value) / clear() / peek().
sig + input identity must both match for a hit. Inputs are compared
by reference (===), exactly what sortQueueJobs needs to invalidate
on a fresh queueJobs array (e.g. backup import).
Coverage:
- empty cache → undefined
- within TTL → cached value
- past TTL → miss (boundary at refreshMs)
- different signature → miss
- different input identity → miss (even with same content)
- overwrite refreshes timestamp
- clear empties everything
- peek reports age + signature for diagnostics
- invalid TTL throws (negative, NaN, non-number)
- TTL=0 means every call misses (immediate expiry)
- default clock works (Date.now)
- large arrays tracked by identity, not value
Renderer rewires _dynamicSortCache to the new helper with a fallback
no-op shim if window.ThrottledCache failed to load. 119/119 green.
