fix(torrents): harden post-release lifecycle boundaries

- make Torrent journals and metadata caches atomic across platforms
- reject unsafe Torrent cache and web-seed inputs
- validate magnet trackers through the shared policy
- preserve embedded web seeds during explicit installation
- correct 1-based Torrent file indices in renderer state and Properties UI

.github/workflows/ci.yml

@@ -71,6 +71,10 @@ jobs:
         run: |
           cargo test --tests --target ${{ matrix.target }}
           cargo test --lib --no-run --target ${{ matrix.target }}
+      - name: Verify Windows atomic Torrent storage
+        if: runner.os == 'Windows'
+        working-directory: src-tauri
+        run: cargo test --test atomic_file --target ${{ matrix.target }} -- --nocapture
       - name: Provision locked engines
         if: runner.os != 'macOS'
         run: node scripts/provision-engines.js --target ${{ matrix.target }}