deploy: bundle pre-built MPP libs for RK3326, update setup script and status

- deploy/arkos/mpp-libs/: add librockchip_mpp.so*, librockchip_vpu.so*,
  libgstrockchipmpp.so — built from source via Docker QEMU (arm64v8/ubuntu:focal)
  using rockchip-linux/mpp + JeffyCN/mirrors@gstreamer-rockchip (-Drga=disabled)
- deploy/arkos/setup_hw_decode.sh: detect mpp-libs/ subdir and install from it
  automatically, no network required; apt fallback retained
- deploy/arkos/mpp-libs/README.md: document origin, target SoC, install steps
- tests/test_video_playback_device.py: on-device GStreamer diagnostic script
- docs/development-status.md: mark MPP HW decode deployed, mppvideodec verified

Verified on physical R36S: mppvideodec found by GStreamer registry with
GST_PLUGIN_PATH=/usr/lib/aarch64-linux-gnu/gstreamer-1.0

deploy/arkos/mpp-libs/README.md

@@ -0,0 +1,38 @@
+# mpp-libs — Pre-built Rockchip MPP libraries for R36S / ArkOS
+
+These `.so` files are compiled for **aarch64 / Ubuntu focal** from:
+
+- **librockchip-mpp** — [github.com/rockchip-linux/mpp](https://github.com/rockchip-linux/mpp) (commit c2c1ee5, 2026-03-10)
+- **gst-mpp** — [github.com/JeffyCN/mirrors, branch gstreamer-rockchip](https://github.com/JeffyCN/mirrors) (RGA disabled)
+
+Built via Docker QEMU (`arm64v8/ubuntu:focal` + `qemu-user-static`).
+
+## Files
+
+| File | Purpose |
+|---|---|
+| `librockchip_mpp.so{,.0,.1}` | Rockchip MPP runtime — hardware VPU abstraction |
+| `librockchip_vpu.so{,.0,.1}` | Rockchip VPU legacy wrapper |
+| `libgstrockchipmpp.so` | GStreamer plugin — exposes `mppvideodec` element |
+
+## Install
+
+Run the parent `setup_hw_decode.sh` as root — it picks up this directory automatically:
+
+```bash
+sudo bash deploy/arkos/setup_hw_decode.sh
+```
+
+Or manually:
+```bash
+sudo cp librockchip_mpp.so* librockchip_vpu.so* /usr/lib/aarch64-linux-gnu/
+sudo cp libgstrockchipmpp.so /usr/lib/aarch64-linux-gnu/gstreamer-1.0/
+sudo ldconfig
+```
+
+## Target
+
+- SoC: RK3326 / PX30 (Cortex-A35)
+- Kernel: 4.4 BSP with `vpu_service` device node at `/dev/vpu_service`
+- ArkOS Ubuntu eoan arm64
+- Requires `/dev/vpu_service` accessible to `video` group (handled by `setup_hw_decode.sh` udev rule)

deploy/arkos/setup_hw_decode.sh

@@ -4,8 +4,11 @@
 # What this script does:
 #   1. Adds a udev rule so the 'video' group can access /dev/vpu_service
 #      (the VPU device used by Rockchip MPP on the kernel 4.4 BSP).
-#   2. Tries to install librockchip-mpp0 and gstreamer1.0-rockchip-mpp.
-#      If they are not in apt, it prints instructions for manual installation.
+#   2. Installs librockchip-mpp and the gst-mpp GStreamer plugin, in order:
+#      a) If a 'mpp-libs/' subdirectory is present next to this script,
+#         copies the pre-built .so files directly (no network required).
+#      b) Otherwise tries apt-get.
+#      c) If apt fails, prints manual installation instructions.
 #
 # Requirements:
 #   - Must be run as root or via sudo.
@@ -67,7 +70,22 @@ info "Verify with: ls -la /dev/vpu_service  (should show crw-rw---- root video)"
 
 MPP_PKGS="librockchip-mpp0 gstreamer1.0-rockchip-mpp"
 
-if apt-cache show librockchip-mpp0 &>/dev/null; then
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+MPP_LIBS_DIR="$SCRIPT_DIR/mpp-libs"
+
+if [[ -d "$MPP_LIBS_DIR" ]]; then
+    info "Found pre-built libraries in $MPP_LIBS_DIR — copying..."
+    # Core MPP runtime
+    for f in "$MPP_LIBS_DIR"/librockchip_mpp.so* "$MPP_LIBS_DIR"/librockchip_vpu.so*; do
+        [[ -e "$f" ]] && cp -v "$f" /usr/lib/aarch64-linux-gnu/
+    done
+    # GStreamer plugin
+    if [[ -f "$MPP_LIBS_DIR/libgstrockchipmpp.so" ]]; then
+        cp -v "$MPP_LIBS_DIR/libgstrockchipmpp.so" /usr/lib/aarch64-linux-gnu/gstreamer-1.0/
+    fi
+    ldconfig
+    info "MPP libraries installed from $MPP_LIBS_DIR."
+elif apt-cache show librockchip-mpp0 &>/dev/null; then
     info "Found librockchip-mpp0 in apt — installing..."
     apt-get install -y $MPP_PKGS
     info "MPP packages installed successfully."