feat(logs): opt-out toggle to bundle diagnostics into terminal paste

Settings > Developer Mode > View Logs now has a toggle (default ON,
persisted to localStorage as qbz-paste-bundle-diagnostics) that
prepends the full System Diagnostics snapshot plus a 10-second cast
scan to the terminal paste upload, so bug reporters share one link
instead of two. Console-tab uploads are unaffected.

- New service module diagnosticsSnapshot.ts centralises the snapshot
  payload (runtime + system + playback + qconnect + optional cast
  scan) so the panel and the paste flow don't drift apart.
- LogsModal shows "Collecting diagnostics..." while the scan is
  running, then "Uploading..." once it hands off to the paste server.

Also revert the auto-run cast scan on the diagnostics panel: bundling
into the paste covers the "one-shot bug report" use case, and the
panel opens instantly again.

cc

src/lib/i18n/locales/de.json

@@ -1355,6 +1355,9 @@
       "uploadSuccess": "Log-URL in Zwischenablage kopiert",
       "uploadError": "Fehler beim Hochladen der Logs",
       "uploading": "Wird hochgeladen...",
+      "bundleDiagnostics": "Systemdiagnose einbeziehen",
+      "bundleDiagnosticsDesc": "Hängt einen Runtime-/System-Snapshot + einen 10s-Cast-Scan an das Terminal-Paste an, damit ein Link alles abdeckt.",
+      "collectingDiagnostics": "Diagnose wird erfasst...",
       "bugReportHint": "Fehler melden? Laden Sie beide Tabs hoch und teilen Sie beide URLs — das hilft uns, Probleme schneller zu beheben. Danke!",
       "verboseLogCapture": "Ausführliche Log-Erfassung",
       "verboseLogCaptureDesc": "Alle Konsolen-Logs erfassen (log/info), nicht nur Fehler. Verwendet mehr Speicher.",