Rename ResourcePool to ReferenceCountedCache — Closes #151

[conradbzura]

Summary

Rename the internal ResourcePool class to ReferenceCountedCache and its companion Resource class to Reference. Rename the module from resourcepool.py to cache.py. The previous names implied a pre-allocated pool of homogeneous resources (like a connection pool), but the actual abstraction is a lazily-created, keyed, reference-counted cache with TTL-based idle eviction. Similarly, Resource was a single-use acquisition handle rather than a resource in the traditional sense -- Reference better describes its role as a reference-counted handle into the cache. All internal references -- imports, type annotations, variable names, docstrings, and test mocks -- are updated accordingly. No behavioral changes.

Closes #151

Proposed changes

Rename module and classes

Rename src/wool/runtime/resourcepool.py to src/wool/runtime/cache.py, rename the ResourcePool class to ReferenceCountedCache, and rename the Resource class to Reference. The CacheEntry nested dataclass retains its name since it already describes its purpose accurately.

Update all internal references

Update every import, type annotation, variable name, docstring cross-reference, and mock patch target across the codebase to reference the new module path (wool.runtime.cache) and class names (ReferenceCountedCache, Reference). Affected modules span the runtime core (__init__.py), discovery layer (discovery/__init__.py, discovery/local.py, discovery/pool.py), worker layer (worker/connection.py, worker/process.py, worker/service.py), and internal documentation (worker/README.md).

Update test references

Rename tests/runtime/test_resourcepool.py to tests/runtime/test_cache.py. Rename test classes: TestResourcePool to TestReferenceCountedCache and TestResource to TestReference. Update all imports, mock patch targets, dependency markers, and docstring references within the test suite. No test logic is changed.

Test cases

All test changes are mechanical renames with no behavioral modifications. The existing test suite validates the same invariants under the new names.

#	Test Suite	Given	When	Then	Coverage Target
1	TestReferenceCountedCache	A cache with a factory	get() is called with a key	Returns a Reference instance	Acquire semantics
2	TestReferenceCountedCache	A cache with active resources	Resources are released	Reference counts decrement to zero	Release semantics
3	TestReferenceCountedCache	A cache with unreferenced entries	TTL expires	Finalizer is called and entry is removed	TTL eviction
4	TestReferenceCountedCache	A cache with a pending TTL cleanup	Resource is reacquired before expiry	Cleanup task is cancelled	Reacquire cancellation
5	TestReferenceCountedCache	A cache with multiple entries	clear() is called	All entries are finalized	Full cleanup
6	TestReferenceCountedCache	A cache with multiple entries	clear(key) is called	Only the targeted entry is finalized	Key-specific cleanup
7	TestReferenceCountedCache	A cache with varied entry states	stats is accessed	Accurate counts for total, referenced, and pending entries	Statistics accuracy
8	TestReferenceCountedCache	A cache used as async context manager	Context is exited	All resources are cleared	Context manager lifecycle
9	TestReferenceCountedCache	A cache under concurrent access	Multiple tasks acquire and release	Pool invariants hold and no resources leak	Concurrency safety
10	TestReference	A Reference from a cache	Used as async context manager	Acquires on enter, releases on exit	Context manager protocol
11	TestReference	A Reference that has already been entered	Entered a second time	Raises RuntimeError	Acquire-once enforcement
12	TestReference	A Reference from a pool that fails during acquire	Entering the context manager	Raises the underlying error and does not mark as acquired	Acquire failure handling
13	TestReference	A Reference that was never acquired	Attempting to exit context	Raises RuntimeError	Release-without-acquire guard
14	TestReference	A Reference that was already released	Attempting to exit context again	Raises RuntimeError	Double-release guard
15	TestSubscriberMeta	No subscriber pool in ContextVar	A subscriber is constructed	A ReferenceCountedCache is set in the ContextVar	Auto-pool initialization