feat: auto-cleanup — archive or delete old recordings, keep disk under control

Closes the Storage-Management loop. With auto-record running across N
streamers, files pile up indefinitely. Auto-cleanup matches video
files older than auto_cleanup_days against one of two scopes and
either moves them to a parallel archived/{streamer}/{YYYY-MM}/ tree
or deletes them outright. Sidecar .chat.json/.chat.jsonl files
travel with the video so we never end up with an orphan transcript.

Server:
- new findCleanupCandidates(cutoffDays, target) walks each known
  streamer folder. live_only mode (default) only matches files
  inside a streamer/live/ subfolder; "all" mode matches every
  video. Files matched by mtime against the cutoff. Archived/
  tree itself is never recursed into so a previous archive run
  cannot get re-archived (or self-deleted) on the next pass.
- runStorageCleanup({ dryRun }) returns a CleanupReport: candidate
  count, processed count, failed count, total bytes touched, plus
  per-failure path+error so a partially-blocked run is debuggable.
  Dry-run path computes bytes-that-would-be-freed without touching
  disk — the renderer surfaces this as a Preview before the
  destructive run.
- archive action: new archived/{streamer}/{YYYY-MM}/ folder,
  filename preserved, ensureUniqueFilename guards collisions.
  delete action: fs.unlinkSync the video and every sidecar.
- Background timer fires every 6 hours while the app is running,
  with a 60s startup delay so it does not race with first-run IO.
  Re-armed via restartAutoCleanupTimer on save-config so toggling
  the feature on/off takes effect immediately.

Renderer:
- Storage settings card extended with the Auto-Cleanup section:
  enable toggle, days threshold, scope (live_only/all), action
  (archive/delete), Preview + Run-now buttons. Preview is
  destructive-action insurance — user can see "would touch N
  files" before pressing Run.
- After a destructive run, the panel auto-refreshes the storage
  stats list so the freed bytes are reflected immediately.
- DE + EN locale strings for every label, button, and report
  message; locale switch live-updates everything.

Settings autosave: enable/days/target/action all included in the
fingerprint so each change persists. autoCleanupDays goes through
the debounced text-input path; the rest are immediate-save
toggles/selects.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/index.html

@@ -604,6 +604,39 @@
                         <p id="storageCardIntro" style="color: var(--text-secondary); font-size:13px; margin-bottom:12px; line-height:1.5;">Disk-Verbrauch pro Streamer im aktuellen Download-Ordner. Live-Aufnahmen werden separat ausgewiesen.</p>
                         <div id="storageSummary" style="color: var(--text-secondary); font-size:12px; margin-bottom:8px;"></div>
                         <div id="storageList"></div>
+
+                        <hr style="border:none; border-top:1px solid var(--border-soft); margin:16px 0;">
+                        <h4 id="cleanupTitle" style="margin:0 0 8px 0; font-size:14px;">Auto-Cleanup</h4>
+                        <p id="cleanupIntro" style="color: var(--text-secondary); font-size:13px; margin-bottom:12px; line-height:1.5;">Aufnahmen aelter als X Tage automatisch archivieren oder loeschen. Schiebt Sidecar-Chat-Dateien (.chat.json/.chat.jsonl) mit der Aufnahme.</p>
+                        <label style="display:flex; align-items:center; gap:8px; margin-bottom: 8px;">
+                            <input type="checkbox" id="autoCleanupEnabledToggle">
+                            <span id="autoCleanupEnabledLabel">Auto-Cleanup aktivieren</span>
+                        </label>
+                        <div class="form-row" style="gap:12px; flex-wrap:wrap; margin-bottom: 8px;">
+                            <label style="display:flex; flex-direction:column; gap:4px; flex:1; min-width:120px;">
+                                <span id="autoCleanupDaysLabel" style="font-size:12px; color:var(--text-secondary);">Tage-Schwelle</span>
+                                <input type="number" id="autoCleanupDays" min="1" max="3650" value="30">
+                            </label>
+                            <label style="display:flex; flex-direction:column; gap:4px; flex:1; min-width:160px;">
+                                <span id="autoCleanupTargetLabel" style="font-size:12px; color:var(--text-secondary);">Bereich</span>
+                                <select id="autoCleanupTarget">
+                                    <option value="live_only" id="autoCleanupTargetLive">Nur Live-Aufnahmen</option>
+                                    <option value="all" id="autoCleanupTargetAll">Alle Aufnahmen</option>
+                                </select>
+                            </label>
+                            <label style="display:flex; flex-direction:column; gap:4px; flex:1; min-width:160px;">
+                                <span id="autoCleanupActionLabel" style="font-size:12px; color:var(--text-secondary);">Aktion</span>
+                                <select id="autoCleanupAction">
+                                    <option value="archive" id="autoCleanupActionArchive">In Archiv verschieben</option>
+                                    <option value="delete" id="autoCleanupActionDelete">Loeschen</option>
+                                </select>
+                            </label>
+                        </div>
+                        <div class="form-row" style="margin-bottom: 8px; gap: 8px;">
+                            <button class="btn-secondary" id="btnCleanupDryRun" onclick="runCleanupDryRun()">Vorschau</button>
+                            <button class="btn-secondary" id="btnCleanupRunNow" onclick="runCleanupNow()">Jetzt ausfuehren</button>
+                        </div>
+                        <div id="cleanupReport" style="color: var(--text-secondary); font-size:12px;"></div>
                     </div>
 
                     <div class="settings-card">