alphax

• Added a runnable package-local example showing a custom transport, request, response body, streaming events, and completion protocol metadata.
• Documented the in-memory cookie-jar constructor for complete API reference coverage.

• Corrected the theme-aware README logo URLs to absolute repository assets so pub.dev and other Markdown renderers load both SVG variants.

• Stabilized the pure-Dart transport-independent request/response, body, stream, file, cancellation, timeout, redirect, middleware, capability, protocol, metrics, and normalized-error contracts.
• Added protocol preference/requirement, truthful fallback, TLS/trust/pinning, proxy, and opaque client-identity policy models.
• Added opt-in replay-aware retries, token authentication with single-flight challenge refresh, in-memory cookies, buffered HTTP caching, and generic circuit-breaker resilience middleware.
• Added the asynchronous AlphaXCookieStore abstraction with atomic updateCookies. The middleware owns cookie parsing/matching while AlphaXCookieJar remains a queued in-memory implementation; persistence remains caller-owned.
• Replaced the URI-only cache store with AlphaXCacheKey/ AlphaXCacheEntry variant-aware storage. Added private-cache defaults, Vary selection, Cache-Control/Date/Age/Expires freshness, credential isolation, Set-Cookie exclusion, ETag/Last-Modified revalidation, 304 metadata merging, bounded entry/byte limits, and mutation invalidation.
• Added HTTP-date Retry-After parsing with the existing bounded retry policy.
• Documented completion-time protocol metadata and intentional provider limitations.

No Flutter or native transport dependency is included in alphax.