Connection manager fixes: folder select, open-all-in-tabs, stable hover

- Folder select showed '(none)' regardless of the actual folder (Angular sets
  [value] on the select before its options render), so 'move out of folder'
  silently saved the old folderId. Per-option [selected] bindings fix both the
  display and the save.
- Folder rows gain 'Open all in tabs': each connection opens in its own new
  tab with the left panel connecting (right stays local); manager closes.
- Folder-row action buttons no longer shift the row on hover (opacity toggle
  instead of display toggle); also canonicalized accent-primary classes.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

ui/src/app/dialogs/chmod-dialog.ts

@@ -36,7 +36,7 @@ const PERMS = ['r', 'w', 'x'] as const;
                       type="checkbox"
                       [checked]="hasBit(r, p)"
                       (change)="toggleBit(r, p)"
-                      class="size-3.5 accent-[var(--primary)]"
+                      class="size-3.5 accent-primary"
                     />
                   </td>
                 }