Drive the connection manager from the keyboard

The manager had only Esc and the scale keys: its list took one Tab stop
per row with no arrows, a stack's rename / delete / open-in-tabs buttons
existed only on hover, and no action had a key.

- Commands (the manager keymap scope, remappable like the rest): new
  connection with focus in Name, new stack, save, connect — or open the
  focused stack in tabs — delete the focused row, rename the focused
  stack, import from WinSCP, close the window.
- The list: up/down/Home/End move focus between rows (focus only:
  loading a connection would discard a half-edited form), Enter opens the
  focused connection, left/right collapse and expand a stack, and a
  stack's actions show while the keyboard is in its row.
- Enter in a form field connects; Esc leaves a field before it closes the
  window; Tab is walked by hand (WKWebView skips buttons and radios); focus
  comes back after a dialog and never stays lost on <body>.
- Tooltips show the keys; the Settings → Keyboard fixed-key list gains the
  manager's.

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

ui/src/app/skins/shadlike/settings-window/settings-window.ts

@@ -36,7 +36,7 @@ const TRANSFER_MODES = ['single', 'multi'] as const;
 const CONCURRENCY_CHOICES = [2, 3, 4, 6, 8] as const;
 
 /** The keys no remap moves, listed read-only under the editable ones. */
-const FIXED_LINES = ['escape', 'escList', 'dialogs', 'menus', 'filter', 'shift', 'find', 'sidebar'] as const;
+const FIXED_LINES = ['escape', 'escList', 'dialogs', 'menus', 'filter', 'shift', 'find', 'manager', 'sidebar'] as const;
 
 /** A recording that could not simply be added: explained under its row. */
 interface CaptureNote {