Make Windows signing non-blocking

Add continue-on-error for signing step to allow unsigned releases
when certificate/password issues occur.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: crisdosaygo

.github/workflows/release.yml

@@ -324,7 +324,8 @@ jobs:
         run: cargo build --release --features production -p fips-pad-ui
 
       - name: Sign binary
-        if: env.WIN_CODESIGN_PFX_B64 != ''
+        if: ${{ secrets.WIN_CODESIGN_PFX_B64 != '' }}
+        continue-on-error: true
         env:
           WIN_CODESIGN_PFX_B64: ${{ secrets.WIN_CODESIGN_PFX_B64 }}
           WIN_PASS: ${{ secrets.WIN_CODESIGN_PFX_PASS }}
@@ -343,7 +344,11 @@ jobs:
               /tr "http://timestamp.digicert.com" /td SHA256 `
               /d "FIPSPad" `
               "target\release\fips-pad.exe"
-            Write-Host "Signed successfully"
+            if ($LASTEXITCODE -ne 0) {
+              Write-Host "Signing failed (exit code $LASTEXITCODE), continuing without signature"
+            } else {
+              Write-Host "Signed successfully"
+            }
           } else {
             Write-Host "signtool not found, skipping"
           }