feat(codec): make client codec selection real — GPU-aware native advertisement

The clients' codec pickers sent a preference the host threw away:
host_wire_caps() hardcoded HEVC for every GPU backend, so the native
path never emitted H.264/AV1 regardless of what the user chose.

Host: advertise what the backend actually encodes, mirroring the
GameStream serverinfo logic — software openh264 emits H.264; probed
backends (Linux VAAPI, Windows AMF/QSV) advertise their per-GPU
CodecSupport via the new wire_mask(); NVENC keeps the
Moonlight-validated H.264|HEVC|AV1 static superset; an empty probe
falls back to the superset so auto clients still resolve HEVC. Gate
10-bit to HEVC (like the 4:4:4 gate) now that a client can steer the
codec — Main10 is the only 10-bit encode path. Fix the web-console
stats label hardcoded to "hevc" (new Codec::label(), shared with the
GameStream register_session mapping).

Android: replace the hardcoded H264|HEVC Hello advertisement with a
videoCodecs param fed by VideoDecoders.decodableCodecBits() (AV1 bit
only when a real hardware video/av01 decoder exists — the decode loop
was already mime-driven); offer AV1 in the codec picker on capable
devices.

Decky: add the missing "Video codec" dropdown (auto/hevc/h264/av1) to
the plugin settings, round-tripping the same codec key the flatpak
client reads.

Apple: unchanged by design (AnnexB.swift is NAL-only, AV1 is never
advertised); refresh the stale "hosts don't emit AV1 on the native
path yet" comments here and host-side.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

clients/android/native/src/session/connect.rs

@@ -76,6 +76,7 @@ pub extern "system" fn Java_io_unom_punktfunk_kit_NativeBridge_nativeConnect<'lo
     gamepad_pref: jint,
     hdr_enabled: jboolean,
     audio_channels: jint,
+    video_codecs: jint,
     preferred_codec: jint,
     timeout_ms: jint,
     launch: JString<'local>,
@@ -142,10 +143,23 @@ pub extern "system" fn Java_io_unom_punktfunk_kit_NativeBridge_nativeConnect<'lo
         // decoder + AAudio layout (read in `crate::audio::AudioPlayback::start`). Anything else
         // normalizes to stereo here.
         punktfunk_core::audio::normalize_channels(audio_channels.clamp(0, u8::MAX as jint) as u8),
-        // Codecs this device can decode — AMediaCodec decodes both HEVC and H.264 (AV1 isn't wired;
-        // hosts don't emit it on the native path yet). The host resolves the emitted codec from these
-        // + the soft `preferred_codec` and echoes it in `connector.codec`, which drives the mime below.
-        punktfunk_core::quic::CODEC_H264 | punktfunk_core::quic::CODEC_HEVC,
+        // Codecs this device can decode, ranked on the Kotlin side (`VideoDecoders.decodableCodecBits`:
+        // H.264 + HEVC always, AV1 when a real `video/av01` decoder exists — AMediaCodec is
+        // mime-driven, see `codec_mime`). Mask to the known bits and fall back to the pre-AV1
+        // H.264|HEVC pair on 0 so a bogus value can't advertise nothing and kill the handshake.
+        // The host resolves the emitted codec from these + the soft `preferred_codec` and echoes it
+        // in `connector.codec`, which drives the mime below.
+        {
+            let bits = (video_codecs.clamp(0, u8::MAX as jint) as u8)
+                & (punktfunk_core::quic::CODEC_H264
+                    | punktfunk_core::quic::CODEC_HEVC
+                    | punktfunk_core::quic::CODEC_AV1);
+            if bits == 0 {
+                punktfunk_core::quic::CODEC_H264 | punktfunk_core::quic::CODEC_HEVC
+            } else {
+                bits
+            }
+        },
         preferred_codec.clamp(0, u8::MAX as jint) as u8,
         launch,   // a store-qualified library id to boot into a game, or None for the desktop
         pin,      // Some → Crypto on host-fp mismatch