Add Account Manager + fix Hybrid-Extract premature extraction

- Account Manager: table UI with add/remove/check for all 4 providers
  (Real-Debrid, Mega-Debrid, BestDebrid, AllDebrid)
- Backend: checkRealDebridAccount, checkAllDebridAccount, checkBestDebridAccount
- Hybrid-Extract fix: check item.fileName for queued items without targetPath,
  disable disk-fallback for multi-part archives, extend disk-fallback to catch
  active downloads by fileName match (prevents CRC errors on incomplete files)

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

src/renderer/styles.css

@@ -1483,6 +1483,70 @@ td {
   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;