DisplaceTransfer added

DisplaceTransfer — switch-map transfer with onDisplace callback

• New transfer: DisplaceTransfer<TInput, TOutput, TInner> — for each input value, creates a new inner async-pushable + subscribable transfer via a factory function, pushes the value into it via asyncPush(), and forwards the inner's emissions to outer subscribers. On each new push(), the previous inner is unsubscribed and destroyed — only the latest inner's emissions pass through. RxJS equivalent: switchMap.
• New factory: createDisplaceTransfer<TInput, TOutput, TInner>().

Documentation

• README — DisplaceTransfer section: New subsection with capabilities, configuration (including onDisplace), RxJS equivalent, code example, and onDisplace usage example with a custom FetchTransfer (abort pattern).
• README — Comparison tables: DisplaceTransfer added to Transfer Comparison Table, Transformation category, operator-equivalent coverage (switchMap→DisplaceTransfer), and Gate/Flow control row.
• README — Debounced search example: Updated to use DisplaceTransfer instead of AsyncConvertTransfer directly, demonstrating switch-map semantics.
• JSDoc: DisplaceTransfer class and createDisplaceTransfer factory fully documented with mechanics, error handling, configuration, and use cases.

Tests

• DisplaceTransfer test suite: 37 tests covering capability flags, basic push & subscribe, displace behavior (cancel previous inner), destroy (dispose inner, clean up subscriptions, idempotent), error handling (factory error with/without onError, previous inner kept active on factory error), real-world scenarios (fetch, WebSocket, readFile, search-as-you-type), async inner transfers (AsyncConvertTransfer, AsyncConditionTransfer), and onDisplace (called with previous inner, not called on first push/destroy, called before destroy, rapid push, custom cleanup, backward-compatible without callback, exception rethrown but inner still destroyed).
• Factory tests: 8 tests for createDisplaceTransfer (type, push, displace, destroy, error handling, async inner).
• Use-case tests: Updated debounced search test to use DisplaceTransfer; added displacement scenario test (slow query cancelled by fast query).
• Coverage: Maintained 100% test coverage (statements, branches, functions, lines) across all 11 source files. Total tests: 2,029.