Revert to v1.5.49 base + fix "Ausgewählte Downloads starten"

- Restore all source files from v1.5.49 (proven stable on both servers)
- Add startPackages() IPC method that starts only specified packages
- Fix context menu "Ausgewählte Downloads starten" to use startPackages()
  instead of start() which was starting ALL enabled packages

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/renderer/styles.css

@@ -1465,88 +1465,6 @@ td {
   }
 }
 
-.account-info {
-  font-size: 13px;
-  padding: 6px 10px;
-  border-radius: 8px;
-  border: 1px solid var(--border);
-  background: var(--field);
-}
-
-.account-info-success {
-  color: #4ade80;
-  border-color: rgba(74, 222, 128, 0.35);
-}
-
-.account-info-error {
-  color: var(--danger);
-  border-color: rgba(244, 63, 94, 0.35);
-}
-
-.account-table {
-  table-layout: fixed;
-  margin-top: 4px;
-}
-
-.account-table th:first-child,
-.account-table td:first-child {
-  width: 22%;
-}
-
-.account-col-hoster {
-  font-weight: 600;
-}
-
-.account-status {
-  display: inline-block;
-  padding: 2px 8px;
-  border-radius: 6px;
-  font-size: 12px;
-  font-weight: 600;
-  line-height: 1.4;
-}
-
-.account-status-ok {
-  background: rgba(74, 222, 128, 0.15);
-  color: #4ade80;
-}
-
-.account-status-configured {
-  background: rgba(245, 158, 11, 0.15);
-  color: #f59e0b;
-}
-
-.account-status-error {
-  background: rgba(244, 63, 94, 0.12);
-  color: var(--danger);
-}
-
-.account-status-loading {
-  background: color-mix(in srgb, var(--accent) 15%, transparent);
-  color: var(--accent);
-}
-
-.account-status-unknown {
-  background: color-mix(in srgb, var(--muted) 15%, transparent);
-  color: var(--muted);
-}
-
-.account-toolbar {
-  display: flex;
-  gap: 8px;
-  margin-top: 4px;
-}
-
-.account-actions-cell {
-  display: flex;
-  gap: 6px;
-}
-
-.account-actions-cell .btn {
-  padding: 4px 8px;
-  font-size: 12px;
-}
-
 .schedule-row {
   display: grid;
   grid-template-columns: 56px auto 56px auto 92px auto auto auto;