fix(ci): force MSVC host toolchain on Windows to prevent dlltool errors

The self-hosted Windows runner has a persistent rustup settings file with
default_host_triple set to x86_64-pc-windows-gnu. This causes rustup to
install the GNU-hosted toolchain, which requires dlltool.exe (not present),
producing flaky builds.

- Add `rustup set default-host x86_64-pc-windows-msvc` before toolchain
  install in both the composite action and the Taskfile
- Pass PINNED_RUST explicitly from the composite action to task ci:setup
  on Windows, bypassing unreliable grep/awk resolution in Task's sh:
- Add host verification to the setup-rust-windows status check

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: pythoninthegrass

.github/actions/setup-tauri-build/action.yml

@@ -41,6 +41,14 @@ runs:
         $gitPath = (Get-ItemProperty 'HKLM:\SOFTWARE\GitForWindows' -ErrorAction SilentlyContinue).InstallPath
         if ($gitPath) { echo "$gitPath\usr\bin" >> $env:GITHUB_PATH }
 
+    - name: Set rustup default host to MSVC (Windows)
+      if: runner.os == 'Windows'
+      shell: pwsh
+      run: |
+        if (Get-Command rustup -ErrorAction SilentlyContinue) {
+          rustup set default-host x86_64-pc-windows-msvc
+        }
+
     - name: Install Task
       uses: go-task/setup-task@v1
 
@@ -129,7 +137,7 @@ runs:
     - name: Setup CI environment (Windows)
       if: runner.os == 'Windows'
       shell: pwsh
-      run: task ci:setup
+      run: task ci:setup PINNED_RUST=${{ steps.rust-version-windows.outputs.toolchain }}
 
     - name: Windows Defender exclusions
       if: runner.os == 'Windows'

taskfiles/ci.yml

@@ -50,12 +50,14 @@ tasks:
     desc: "Configure rustup nightly toolchain (Windows)"
     platforms: [windows]
     cmds:
+      - rustup set default-host x86_64-pc-windows-msvc
       - rustup toolchain install {{.PINNED_RUST}} --profile minimal --no-self-update --target x86_64-pc-windows-msvc
       - rustup default {{.PINNED_RUST}}
       - rustc --version
       - cargo --version
     status:
       - rustup run {{.PINNED_RUST}} rustc --version
+      - rustup run {{.PINNED_RUST}} rustc --version --verbose | findstr "host: x86_64-pc-windows-msvc"
       - rustup target list --installed --toolchain {{.PINNED_RUST}} | findstr x86_64-pc-windows-msvc
 
   setup-cargo-tools: