Implement optional Skia codec adapter (#41)

RUSTREWRITE.md

@@ -414,7 +414,7 @@ MSRV, features, and licenses at adoption time.
 | compression and tar archives | [`flate2` 1.1.9](https://crates.io/crates/flate2/1.1.9), [`tar` 0.4.46](https://crates.io/crates/tar/0.4.46) | Enforce decompressed-size, path traversal, and entry-count limits on untrusted OAR data. |
 | XML and URL | [`quick-xml` 0.41.0](https://crates.io/crates/quick-xml/0.41.0), [`url` 2.5.8](https://crates.io/crates/url/2.5.8), [`base64` 0.23.1](https://crates.io/crates/base64/0.23.1) | Streaming XML for LLSD/login; retain exact URL escaping behavior with fixtures. |
 | CoreJ2K 2.3.3.91 | system [OpenJPEG](https://www.openjpeg.org/) 2.5.4+ through the private `libremetaverse-openjpeg` adapter | Opt-in `jpeg2000` feature; checked-in minimal bindings avoid a libclang build dependency. Bounded memory streams and header validation isolate native code. Golden tests cover channel order, alpha, 16-bit precision, dimensions, discard levels, lossless/lossy modes, and malformed input. |
-| SkiaSharp 4.150.1 | [`skia-safe` 0.99.0](https://crates.io/crates/skia-safe/0.99.0) | MSRV 1.85 and native/binary-cache build. Optional adapter only; core image APIs must not leak Skia types. |
+| SkiaSharp 4.150.1 | [`skia-safe` 0.99.0](https://crates.io/crates/skia-safe/0.99.0) | Adopted behind the opt-in `skia` feature. Target-specific official binary-cache feature sets provide BMP/GIF/ICO/JPEG/PNG/WBMP/WebP decoding on macOS, Linux, and Windows; checked owned buffers keep Skia types out of the core image API. |
 | Pfim 0.11.4 | [`image` 0.25.10](https://crates.io/crates/image/0.25.10), [`ddsfile` 0.6.0](https://crates.io/crates/ddsfile/0.6.0) | `image` covers TGA and common DDS decoding; `ddsfile` exposes DDS container details. Golden files decide whether both are needed. |
 | OggVorbisEncoder 1.2.2 | [`vorbis_rs` 0.5.6](https://crates.io/crates/vorbis_rs/0.5.6) | BSD-3-Clause, MSRV 1.82, backed by C libraries. Feature-gate native audio encoding. |
 | SIPSorcery 8.0.23 | [`webrtc` 0.20.0](https://crates.io/crates/webrtc/0.20.0), [`cpal` 0.18.1](https://crates.io/crates/cpal/0.18.1), [`opus` 0.3.1](https://crates.io/crates/opus/0.3.1) | Validate SDP, ICE, data-channel framing, audio formats, device hotplug, and native libopus deployment separately. Do not claim parity from successful compilation. |