feat(cache): add unified Cache

[tomas-zijdemans]

This PR replaces LruCache and TtlCache with a single Cache<K, V> that unifies LRU eviction, TTL expiration, stale-while-revalidate, and load-through (getOrLoad).

The existing caches extend Map, so inherited methods bypass LRU/TTL logic entirely. Both subclass Map, making it structurally impossible to compose LRU with TTL.

Cache<K, V> uses composition over inheritance: it owns a Map for storage and delegates to IndexedHeap for deadline-ordered expiration. Mode is determined by options, not class choice, and a discriminated union on CacheOptions makes illegal combinations compile-time errors.

Beyond fixing the structural issues, this introduces capabilities that didn't exist before:

• Combined LRU + TTL in a single cache
• Renames the base type to CacheLike, a more natural type name
• getOrLoad(key, loader) with automatic in-flight deduplication
• Stale-while-revalidate with background refresh, error handling, and configurable soft/hard TTL thresholds
• Per-entry TTL overrides and sliding expiration
• Single heap-driven timer replacing per-entry setTimeouts
• Hit/miss/eviction stats, typed ejection reasons, and Symbol.dispose

Since @std/cache is still experimental (0.2.2), this is the right time to make a clean break before stabilization locks things in.

Bonus: The new Cache has significant performance improvements for real-life workflows (e.g. in my testing, write-heavy workloads (set, eviction) are 4-22x faster. hot-key reads are 55x faster thanks to a linked-list)

[codecov]

Codecov Report

❌ Patch coverage is 99.79296% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 94.60%. Comparing base (f0c9f14) to head (7138d78).

Files with missing lines	Patch %	Lines
cache/cache.ts	99.79%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7082      +/-   ##
==========================================
+ Coverage   94.57%   94.60%   +0.02%     
==========================================
  Files         636      635       -1     
  Lines       52138    52398     +260     
  Branches     9399     9464      +65     
==========================================
+ Hits        49311    49572     +261     
  Misses       2249     2249              
+ Partials      578      577       -1     

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[bartlomieju]

I'll hold on reviewing this one until #7076 lands.

[bartlomieju]

This needs a rebase — there are conflicts with main that need resolving.

Two inline comments below.

[tomas-zijdemans]

Thanks,

• Extracted a new exported CacheOptionsShared<K, V> interface as suggested with maxSize and onRemove. CacheOptionsBase, CacheOptionsTtl, and CacheOptionsSwr now extend it.
• Defensive guard added in #onTimer as suggested

[tomas-zijdemans]

Renamed MemoizationCache to CacheLike and moved it to the base file (cache.ts)

[tomas-zijdemans]

Not sure if this should have "BREAKING" in the PR title, since the module is not stable 🤷 . Changing it based on the comment here: #7117 (comment)

Ready for review! 😁