Build the Bonsai Viewer in CI with the Autodesk connector bundled

Compile the Bonsai Viewer as part of the Linux and Windows binary builds,
and ship the Autodesk connector alongside the viewer executable.

Qt6 dependencies:
- The viewer links Qt6::Svg for runtime icon tinting. Svg is a separate
  base-Qt archive, so aqt now installs "qtbase qtsvg" (plus icu on Linux)
  rather than qtbase alone, on both Linux and Windows.
- Qt6::CorePrivate is exposed differently across Qt versions: Qt 6.8 ships
  the target inside Qt6Core, while Qt 6.10 provides it only as a separate
  CorePrivate config package. The viewer CMakeLists requests it via
  OPTIONAL_COMPONENTS so it resolves on both.
- When cross-compiling Windows ARM64, windeployqt runs from the host x64
  Qt, so qtsvg is installed into the host Qt as well.

Windows build:
- build-all-win.py passed -DBUILD_IFCVIEWER, a flag since renamed to
  BUILD_BONSAIVIEWER, so the Windows build compiled no viewer at all. It
  now passes -DBUILD_BONSAIVIEWER.
- The Autodesk connector is bundled under connectors/ next to
  BonsaiViewer.exe in the packaged archive, mirroring the Linux builds.
- The Windows workflow builds the connector (PyInstaller) before the main
  build so it is available to bundle.

Connector bundling:
- The Linux rocky workflows build the connector and bundle it into the
  BonsaiViewer archive; the Windows build now does the same.

Generated with the assistance of an AI coding tool.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

nix/build-all.py

@@ -805,7 +805,8 @@ def install_qt6() -> str:
 
     qt_config = qt_dir / "lib" / "cmake" / "Qt6" / "Qt6Config.cmake"
     qt_core = qt_dir / "lib" / "libQt6Core.so.6"
-    if qt_config.exists() and qt_core.exists():
+    qt_svg = qt_dir / "lib" / "cmake" / "Qt6Svg" / "Qt6SvgConfig.cmake"
+    if qt_config.exists() and qt_core.exists() and qt_svg.exists():
         logger.info(f"Found existing Qt6 at {qt_dir}, skipping")
         return str(qt_dir)
 
@@ -822,13 +823,17 @@ def install_qt6() -> str:
             qt_arch,
             "-O",
             str(qt_install_root),
+            # Keep the install lean by filtering archives: qtbase provides
+            # Core/Gui/Widgets (and the Qt6::CorePrivate target), qtsvg provides
+            # Qt6::Svg. Both are base-Qt archives, not add-on modules.
             "--archives",
             "icu",
             "qtbase",
+            "qtsvg",
         ]
     )
 
-    if not qt_config.exists() or not qt_core.exists():
+    if not (qt_config.exists() and qt_core.exists() and qt_svg.exists()):
         raise RuntimeError(f"Qt6 installation did not produce a usable Qt at {qt_dir}.")
 
     return str(qt_dir)