Ship portable CPU dispatch and verified shared runtime dependencies

docs/BUILDING.md

@@ -135,10 +135,17 @@ The generated `.searchi/packages/searchi-windows.zip` contains the desktop,
 matching-architecture Google worker, FFmpeg/FFprobe and notices. It excludes
 model caches, local settings and indexes. `PACKAGE.json` records SHA-256 for
 each included file. Extract the entire archive before launching `searchi.exe`.
-First launch uses normal verified model setup. WebView2 and the applicable
-Microsoft C++ runtime remain Windows prerequisites. The Windows archive includes
+First launch uses normal verified model setup. WebView2 remains a Windows
+prerequisite. The normal x64 archive ships unchanged Microsoft release CRT
+DLLs with their redistribution notice; Visual Studio is not required to run it.
+The Windows archive includes baseline and optimized CPU modules, selected
+using CPU and OS capabilities, and
 the verified Vulkan loader DLL and its license; GPU availability is detected at
 runtime, with CPU fallback. The SDK is used only to compile the app.
+All runtime DLLs are listed by size and SHA-256 in `runtime-libraries.json`.
+Staging and packaging reject missing or changed listed dependencies before
+replacing output. CPU-only VM smoke tests can also omit optimized modules to
+exercise the packaged baseline; this does not certify older physical hardware.
 
 This is an unsigned development archive, not a production installer. Native
 launch, clean-machine dependencies, upgrades and signatures must still be