Document Linux AppImage viewer packaging

Author: chammoru

docs/PORTING_STATUS.md

@@ -87,14 +87,14 @@ It does not yet implement:
 - Existing MFC Viewer feature parity.
 - Video playback.
 - Comparer features.
-- Full Linux AppImage/AppDir packaging.
+- Release integration for the experimental Qt viewer artifacts.
 
 Successful Qt viewer CI runs:
 
 - https://github.com/chammoru/Q1View/actions/runs/26217369518
 - https://github.com/chammoru/Q1View/actions/runs/26224574718
 - https://github.com/chammoru/Q1View/actions/runs/26224816758
-- Latest verified run: https://github.com/chammoru/Q1View/actions/runs/26230650595
+- Latest verified run: https://github.com/chammoru/Q1View/actions/runs/26231241422
 
 Artifacts were produced for:
 
@@ -105,7 +105,7 @@ Artifacts were produced for:
 Latest artifact notes:
 
 - Windows and macOS artifacts include Qt deployment output from `windeployqt`/`macdeployqt`.
-- Linux currently uploads the viewer executable, a small launch script, and runtime notes. It still expects Qt 6 runtime libraries and the xcb platform plugin to exist on the target Linux system.
+- Linux now uploads an AppImage/AppDir package built with `linuxdeploy` and `linuxdeploy-plugin-qt`.
 
 Relevant files:
 
@@ -115,6 +115,8 @@ Relevant files:
 - `ViewerQt/RawOpenDialog.h`
 - `ViewerQt/RawOpenDialog.cpp`
 - `.github/workflows/viewer-qt.yml`
+- `packaging/linux/q1view-viewer-qt.desktop`
+- `packaging/linux/q1view-viewer-qt.svg`
 - `CMakeLists.txt`
 
 ## Current Build Commands
@@ -142,7 +144,7 @@ Local machine note: this Windows machine did not have `cmake`, `cl`, `gcc`, or `
 2. Improve packaging for `q1view_viewer_qt`:
    - Windows packaging uses `windeployqt`.
    - macOS packaging uses `macdeployqt`.
-   - Linux currently uploads an executable, wrapper script, and runtime notes; replace with AppDir/AppImage or another self-contained bundle.
+   - Linux packaging now builds an AppImage; next verify it manually on a clean Linux desktop.
 3. Improve raw image workflows:
    - Add validation/test fixtures for representative raw formats.
 4. Add a minimal automated Qt smoke check if practical: