fix(ci): remove --bundles flag from Tauri debug build, update deprecated actions

--bundles app is macOS-only; on Windows valid values are msi/nsis. The real fix
is to simply not set TAURI_SIGNING_PRIVATE_KEY at all (unset env var tells Tauri
to skip signing, unlike empty string which causes decode failure).

Also update actions/checkout and dorny/paths-filter to versions that support
Node.js 24 to resolve deprecation warnings.

---
Developed by Claude Sonnet 4.6

Author: houke

.github/workflows/fluxby-pr-check.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup Node.js
         uses: actions/setup-node@v4
@@ -56,10 +56,10 @@ jobs:
       tauri: ${{ steps.filter.outputs.tauri }}
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Check for Tauri-related changes
-        uses: dorny/paths-filter@v3
+        uses: dorny/paths-filter@v4
         id: filter
         with:
           filters: |
@@ -83,7 +83,7 @@ jobs:
     runs-on: ${{ matrix.platform }}
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup Node.js
         uses: actions/setup-node@v4
@@ -122,4 +122,4 @@ jobs:
 
       - name: Build Tauri app (debug)
         working-directory: apps/tauri
-        run: npx tauri build --debug --bundles app
+        run: npx tauri build --debug

.github/workflows/fluxby-release.yml

@@ -23,7 +23,7 @@ jobs:
       dry_run: ${{ github.event.inputs.dry_run || 'false' }}
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
           token: ${{ secrets.GITHUB_TOKEN }}
@@ -224,7 +224,7 @@ jobs:
       release_id: ${{ steps.create-release.outputs.id }}
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Download changelog artifact
         uses: actions/download-artifact@v4
@@ -297,7 +297,7 @@ jobs:
     runs-on: ${{ matrix.platform }}
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           ref: v${{ needs.initialize-release.outputs.version }}