Read the version from build_scripts/compile_version_string.txt

The CMake build had the version hard-coded as 5.7.4, while the qmake build
read it from compile_version_string.txt (5.8.17-release). The stale number
also made the version check report an update. As in the qmake build, the
full string becomes APPLICATION_VERSION and its numeric part the project
version.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/steamframe/PROGRESS.md

@@ -149,7 +149,7 @@
   - GLIBC ≤ 2.38 (the Frame has 2.39); GLIBCXX ≤ 3.4.32 (not checked against the Frame).
   - NEEDED: Qt6 Core/Gui/Qml/Quick/Widgets/Network/DBus/Multimedia/WebSockets, libX11,
     libXtst, libpulse, libopenvr_api, libstdc++/libc.
-- **Package** `dist/AdvancedSettings-5.7.4-linux-arm64.tar.gz`: 3.0 MB (9.1 MB unpacked).
+- **Package** `dist/AdvancedSettings-5.7.4-linux-arm64.tar.gz`: 3.0 MB (9.1 MB unpacked); since the version fix below `…-5.8.17-…`.
   The version 5.7.4 comes from `qt6`'s `project()` (master is at 5.8.17).
 
 **Open (needs the Frame):**
@@ -157,6 +157,18 @@
   (Material), Layouts, Dialogs, Multimedia.
 - Do libXt/libXtst exist on SteamOS? Is libstdc++ new enough?
 
+### Version from `compile_version_string.txt` (2026-10-07)
+
+- **Problem:** `qt6`'s `CMakeLists.txt` had the version hard-coded as 5.7.4. The qmake build
+  read it from `build_scripts/compile_version_string.txt` (`5.8.17-release`). `master` is
+  fully merged into `qt6`, so only the number was stale. Consequence: the version check
+  (comparison with `ver/versioncheck.json`, 5.8.17) would have reported an update.
+- **Fix:** CMake reads the file.
+  - `APPLICATION_VERSION` = full string, as in qmake.
+  - `project(VERSION)` = numeric part.
+- **Result:** `APPLICATION_VERSION="5.8.17-release"`, `CMAKE_PROJECT_VERSION=5.8.17`, package
+  `dist/AdvancedSettings-5.8.17-linux-arm64.tar.gz` (3.0 MB).
+
 ### Test checklist on the Frame (step 5)
 
 Deploy: `build_scripts/steamframe/deploy-to-frame.sh <user>@<frame>` (SteamVR running).