Register InterpreterDispatch.cpp/.h in the UWP project; update AGENTS.md

Core/MIPS/InterpreterDispatch.cpp landed without being added to
UWP/CoreUWP/CoreUWP.vcxproj / .vcxproj.filters, breaking the UWP build
(CMake and the main Core.vcxproj build both succeed silently, so this
only surfaces when someone actually builds the UWP project). Verified
the fix by building CoreUWP directly via UWP/PPSSPP_UWP.sln.

Also updates AGENTS.md's "new .cpp/.c file" checklist from five places
to seven (adding the two UWP project files), documents that the UWP
build can actually be build-tested here via MSBuild rather than just
eyeballed, and notes this exact miss so it's easier to catch next time.

Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_019SKhm9wKEQzRUsx9mTrrtQ

AGENTS.md

@@ -180,12 +180,26 @@ small examples to copy from). A module is a `const HLEFunction <name>[]` table o
   the `// add new modules here.` comment near the end of that function) - not inserted alphabetically/logically among
   the existing `Register_*()` calls. Module registration order affects numeric IDs used in savestates, so inserting a
   new module earlier in that list would break save-state compatibility for saves made with older builds.
-- Remember to add any new `.cpp`/`.c` file to **five** places: `Core/CMakeLists.txt`, `Core/Core.vcxproj`,
-  `Core/Core.vcxproj.filters`, `android/jni/Android.mk`, and `libretro/Makefile.common`. New `.h` files only need the
-  first three (`Android.mk`/`Makefile.common` are plain compiled-source lists so headers
-  don't go in them). Only the CMakeLists.txt change can be verified from a Linux/Mac build - the rest can't be
-  build-tested here, so double check them by hand against how an existing neighboring file (e.g. `sceVaudio.cpp`) is
-  listed in each. Note: New files in the unittest project have to be updated in the unittest part in android/jni/Android.mk.
+- Remember to add any new `.cpp`/`.c` file to **seven** places: `Core/CMakeLists.txt`, `Core/Core.vcxproj`,
+  `Core/Core.vcxproj.filters`, `UWP/CoreUWP/CoreUWP.vcxproj`, `UWP/CoreUWP/CoreUWP.vcxproj.filters`,
+  `android/jni/Android.mk`, and `libretro/Makefile.common`. New `.h` files need the first five (everything except
+  `Android.mk`/`Makefile.common`, which are plain compiled-source lists so headers don't go in them). Double check
+  each by hand against how an existing neighboring file (e.g. `sceVaudio.cpp`) is listed. Forgetting the UWP entries
+  is easy to miss - the CMake and MSBuild (`Core.vcxproj`) builds both succeed silently, and it only surfaces as a
+  UWP-only build failure (this has happened for real: `Core/MIPS/InterpreterDispatch.cpp` landed without its UWP
+  entries, and the omission wasn't caught until someone actually built the UWP project). Note: New files in the
+  unittest project have to be updated in the unittest part in android/jni/Android.mk.
+
+  Both the CMakeLists.txt change (via a Linux/Mac build) and the `Core.vcxproj`/UWP changes (via MSBuild on Windows)
+  can actually be build-tested, not just eyeballed - see "Build and Validation" above for the main Windows solution,
+  and for UWP specifically:
+  ```powershell
+  $installPath = & "C:\Program Files (x86)\Microsoft Visual Studio\Installer\vswhere.exe" -latest -property installationPath
+  $msbuild = "$installPath\MSBuild\Current\Bin\MSBuild.exe"
+  & $msbuild "UWP\PPSSPP_UWP.sln" /t:CoreUWP /p:Configuration=Debug /p:Platform=x64 /m
+  ```
+  (only `android/jni/Android.mk` and `libretro/Makefile.common` genuinely can't be build-tested here - see their
+  respective sections above for what verification is possible for those.)
 
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