Codecs and clients

What's Changed

• Enable zero-copy payload extraction for codecs by @leynos in #420
• Migrate from cucumber to rstest bdd by @leynos in #423
• Decompose oversized fragment transport test into modular files by @leynos in #425
• Refactor connection module into submodules by @leynos in #424
• Replace response and multi_packet with ActiveOutput enum by @leynos in #427
• Replace #[allow] with #[expect] in tests and annotate by @leynos in #438
• Move FairnessConfig to fairness module and re-export by @leynos in #437
• Refactor fragmentation: move fragment_packet to fragment crate by @leynos in #436
• Rename BackoffConfig.normalised to normalized (US spelling) by @leynos in #446
• Align docs to en-GB-oxendict spelling; add migration guide by @leynos in #440
• Refactor app module into focused submodules by @leynos in #447
• Fix readiness signal ownership compile error by @leynos in #444
• Refactor echo example to use opaque app boundary errors by @leynos in #442
• Refactor exponential backoff test to remove sleeps by @leynos in #443
• Rename payload() to into_payload() across codebase by @leynos in #445
• Improve WireframeProtocol docs and fragment tests header by @leynos in #452
• Gate client, extractor, and request modules behind not(loom) flag by @leynos in #451
• Refactor errors, buffer sizing, tests, and docs; add fixtures by @leynos in #456
• Add timeout handling and refactor connection checks in tests by @leynos in #450
• Centralize integration test helpers in wireframe_testing (integration_helpers) by @leynos in #453
• Refactor: modularize into submodules; rebase onto origin/main by @leynos in #448
• Map client decode/transport failures to WireframeError (complete) by @leynos in #459
• FragmentAdapter trait and DefaultFragmentAdapter; opt-in fragmentation by @leynos in #457
• Refactor: preserve EofError in io::Error via type-safe downcast by @leynos in #454
• Add AppDataStore and byte_order utilities; refactor app data sharing by @leynos in #455
• Integrate inbound MessageAssembler; add assembly helper and routing by @leynos in #458
• Add ExecPlan docs for API cleanup critique by @leynos in #464
• Client streaming: ResponseStream API for multi-packet responses by @leynos in #462
• Unify outbound codec path with FramePipeline & CodecDriver by @leynos in #461
• Unify test-support feature gate and remove test-helpers by @leynos in #466
• MemoryBudgets type and per-connection budgets builder (8.3.1) by @leynos in #463
• Enable doctests (COMPLETE): add benchmark script and docs by @leynos in #467
• Public API surface cleanup: modular exports and prelude by @leynos in #470
• Complete: property-based round-trip tests for default and mock codecs by @leynos in #469
• Add developers guide and vocabulary normalization docs by @leynos in #471
• Rename connection modules to inbound_handler and connection_spawner by @leynos in #472
• Add interleaved push queues tests (unit/BDD) and docs by @leynos in #473
• Implement memory budget enforcement across message assembly (8.3.2) by @leynos in #474
• Decouple Message Encoding from Bincode: Adapters, Context & SerdeBridge by @leynos in #475
• Implement interleaved queue parity tests and ExecPlan living doc by @leynos in #468
• Implement soft-limit memory back-pressure for inbound reads (8.3.3) by @leynos in #478
• Publish client echo-login example, API docs, and ExecPlan by @leynos in #477
• Complete 9.6.1 Codec Performance Benchmarks, Tests, and Docs by @leynos in #476
• Refactor backpressure test strings to use concat by @leynos in #479
• Implement hard-cap memory-budget protection (8.3.4) by @leynos in #483
• Extend wireframe_testing with codec-aware drivers and app codec by @leynos in #484
• Add client request hooks for outgoing requests and incoming frames by @leynos in #482
• Refactor codec benchmark support into fragmentation/allocation modules by @leynos in #481
• Define derived defaults for connection memory budgets by @leynos in #486
• Implement outbound streaming send_streaming with tests (8.4.1–8.4.5) by @leynos in #485
• Add Hotline codec fixtures and tests for wireframe_testing by @leynos in #487
• Add tests and docs for per-connection memory budgets (8.3.6) by @leynos in #489
• Add utilities for feeding partial frames and fragments (tests, docs, re-exports) by @leynos in #493
• Implement structured logging, tracing spans, and TracingConfig API by @leynos in #488
• Refactor budget config parsing and standardize error handling by @leynos in #494
• Introduce test observability harness with ObservabilityHandle and obs_handle fixture by @leynos in #491
• Add configurable Wireframe pool with per-socket in-flight and preamble by @leynos in #496
• Add slow reader/writer back-pressure testkit, tests, and docs by @leynos in #495
• Add CodecError Regression Tests with wireframe_testing and ExecPlan by @leynos in #497
• Docs: rewrite user-guide to remove first-person pronouns by @leynos in #502
• Centralize streaming inbound assertions; add ExecPlan doc and tests by @leynos in #501
• feat(client-pool): expose PoolHandle API with fair scheduling and graceful shutdown by @leynos in #498
• Improve waiter queue error handling with PoolFairnessPolicy by @leynos in #506
• 8.5.3: Remove duplicate accessors in message assembly by @leynos in #499
• Formal verification methods by @leynos in #510
• Promote formal verification to tasks; renumber roadmap items by @leynos in #511
• Add mutation testing ADR and execplan by @leynos in #512
• Add 11-4-2 ExecPlan doc and tests; mark 12.4.2 roadmap done by @leynos in #509
• Export testkit utilities behind wireframe::testkit feature (Stage A) by @leynos in #507
• Add StreamingResponseExt trait and TypedResponseStream adapter by @leynos in #508
• Update mutation testing ADR and execution plan with change-detection by @leynos in #516
• Verify and fix documented code issues; Whitaker lint CI and docs by @leynos in #514
• Publish in-process server-client pair test harness (12.3.2) by @leynos in #515
• Fix British spelling: signaling -> signalling in tests by @leynos in #517
• Migration guide by @leynos in #518

Full Changelog: v0.2.0...v0.3.0