Update tauri-build.yml (#4978)

# Description of Changes

<!--
Please provide a summary of the changes, including:

- What was changed
- Why the change was made
- Any challenges encountered

Closes #(issue_number)
-->

---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### Translations (if applicable)

- [ ] I ran
[`scripts/counter_translation.py`](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/docs/counter_translation.md)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.

.github/workflows/tauri-build.yml

@@ -92,8 +92,6 @@ jobs:
           toolchain: stable
           targets: ${{ (matrix.platform == 'macos-15' || matrix.platform == 'macos-15-intel') && 'aarch64-apple-darwin,x86_64-apple-darwin' || '' }}
 
-
-
       - name: Set up JDK 21
         uses: actions/setup-java@c5195efecf7bdfc987ee8bae7a71cb8b11521c00 # v4.7.1
         with:
@@ -180,7 +178,7 @@ jobs:
       # DigiCert KeyLocker Setup (Cloud HSM)
       - name: Setup DigiCert KeyLocker
         id: digicert-setup
-        if: ${{ matrix.platform == 'windows-latest' && env.SM_API_KEY != '' }}
+        if: ${{ matrix.platform == 'windows-latest' && env.SM_API_KEY != '' && github.ref == 'refs/heads/main' }}
         uses: digicert/ssm-code-signing@v1.1.0
         env:
           SM_API_KEY: ${{ secrets.SM_API_KEY }}
@@ -190,7 +188,7 @@ jobs:
           SM_HOST: ${{ secrets.SM_HOST }}
 
       - name: Setup DigiCert KeyLocker Certificate
-        if: ${{ matrix.platform == 'windows-latest' && env.SM_API_KEY != '' }}
+        if: ${{ matrix.platform == 'windows-latest' && env.SM_API_KEY != '' && github.ref == 'refs/heads/main' }}
         shell: pwsh
         run: |
           Write-Host "Setting up DigiCert KeyLocker environment..."
@@ -225,7 +223,7 @@ jobs:
 
       # Traditional PFX Certificate Import (fallback if KeyLocker not configured)
       - name: Import Windows Code Signing Certificate
-        if: ${{ matrix.platform == 'windows-latest' && env.SM_API_KEY == '' }}
+        if: ${{ matrix.platform == 'windows-latest' && env.SM_API_KEY == '' && github.ref == 'refs/heads/main' }}
         env:
           WINDOWS_CERTIFICATE: ${{ secrets.WINDOWS_CERTIFICATE }}
           WINDOWS_CERTIFICATE_PASSWORD: ${{ secrets.WINDOWS_CERTIFICATE_PASSWORD }}
@@ -314,7 +312,8 @@ jobs:
           TAURI_SIGNING_PRIVATE_KEY_PASSWORD: ${{ secrets.TAURI_SIGNING_PRIVATE_KEY_PASSWORD }}
           VITE_SUPABASE_PUBLISHABLE_DEFAULT_KEY: ${{ secrets.VITE_SUPABASE_PUBLISHABLE_DEFAULT_KEY }}
           VITE_SAAS_SERVER_URL: ${{ secrets.VITE_SAAS_SERVER_URL }}
-          SIGN: ${{ (env.SM_API_KEY == '' && env.WINDOWS_CERTIFICATE != '') && '1' || '0' }}
+          # Only enable Windows signing in Tauri when on main
+          SIGN: ${{ github.ref == 'refs/heads/main' && (env.SM_API_KEY == '' && env.WINDOWS_CERTIFICATE != '') && '1' || '0' }}
           CI: true
         with:
           projectPath: ./frontend
@@ -323,7 +322,7 @@ jobs:
 
       # Sign with DigiCert KeyLocker (post-build)
       - name: Sign Windows binaries with DigiCert KeyLocker
-        if: ${{ matrix.platform == 'windows-latest' && env.SM_API_KEY != '' }}
+        if: ${{ matrix.platform == 'windows-latest' && env.SM_API_KEY != '' && github.ref == 'refs/heads/main' }}
         shell: pwsh
         run: |
           Write-Host "=== DigiCert KeyLocker Signing ==="
@@ -514,7 +513,7 @@ jobs:
           fi
 
       - name: Verify Windows Code Signature
-        if: matrix.platform == 'windows-latest'
+        if: matrix.platform == 'windows-latest' && github.ref == 'refs/heads/main'
         shell: pwsh
         run: |
           Write-Host "Verifying Windows code signatures..."