Fix the dead win7 context menu, flatten the selection, add a tab menu

Right-click did nothing under the win7 skin, and then swallowed the next
click. 7.css declares `position: relative` on ul[role=menu] and the `skin`
layer outranks `utilities`, so Tailwind's `.fixed` lost: [style.left/top.px]
became flow offsets from the menu's static position — the last child of the
h-screen frame — and every menu rendered below the viewport, unreachable
behind overflow:hidden. Its backdrop is a plain <div>, unmatched by 7.css, so
that stayed genuinely fixed and ate the following click. Regressed in 0ae2a62,
when the menu adopted 7.css's real markup.

Restated `position: fixed` in skinfix, scoped to a new `w7-ctx` marker so
7.css's own menus keep theirs. scripts/menu-probe.ts is the regression test:
it renders the menu at declared coordinates, pixel-scans whether it landed
there, and carries a marker-less control menu (the bug verbatim) as its own
discriminator. A resting pixel diff cannot see this class of bug.

Selection band goes flat: --w7-sel-bg/-bd (#cbe8f6/#26a0da) is what Explorer
actually painted, where 7.css reused --w7-el-grad-h, its Aero element-hover
ramp. That var is left alone — buttons and tabs still want the gloss. The
unfocused pane gets the grey idle band; the band still never disappears with
focus, it only weakens. Harness diff confirms the change touches selection
rows and nothing else, in both themes.

New workspace-tab right-click menu in both skins: New Tab, Close Tab, Close
Other Tabs, Close Tabs to the Right, Disconnect. The target id travels inside
the action string because the right-clicked tab is not necessarily the active
one. Illegal entries are disabled rather than omitted, the way Win7 greyed
out — and since 7.css's [aria-disabled] handling is CSS-only, the keyboard
paths check the flag themselves.

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

ui/src/app/core/panels.service.ts

@@ -398,6 +398,46 @@ export class PanelsService {
     this.refocus();
   }
 
+  /**
+   * Close every tab except one — the tab menu's "Close Other Tabs".
+   *
+   * Snapshot the ids FIRST: closeWorkspace mutates the list on every call, so
+   * iterating the live signal would skip half of them. It also refuses the
+   * last tab, which is exactly the wanted floor here.
+   */
+  closeOtherWorkspaces(id: number): void {
+    for (const other of this.workspaces().map((w) => w.id)) {
+      if (other !== id) this.closeWorkspace(other);
+    }
+    this.setActiveWorkspace(id);
+  }
+
+  /** Close every tab to the right of one, in visual order. */
+  closeWorkspacesToRight(id: number): void {
+    const list = this.workspaces();
+    const index = list.findIndex((w) => w.id === id);
+    if (index < 0) return;
+    for (const target of list.slice(index + 1).map((w) => w.id)) {
+      this.closeWorkspace(target);
+    }
+  }
+
+  /**
+   * Drop both of a tab's remote sessions, keeping the tab itself. Unlike
+   * `disconnectPanel` this targets a tab by id, because the right-clicked tab
+   * is not necessarily the active one.
+   */
+  async disconnectWorkspace(id: number): Promise<void> {
+    const workspace = this.workspaces().find((w) => w.id === id);
+    if (!workspace) return;
+    for (const panel of [workspace.left, workspace.right]) {
+      const sessionId = panel.sessionId();
+      if (sessionId === 'local') continue;
+      await this.rpc.request.disconnect({ sessionId });
+      this.resetToLocal(panel);
+    }
+  }
+
   setActiveWorkspace(id: number): void {
     if (this.activeWorkspaceId() !== id) {
       this.activeWorkspaceId.set(id);