feat: v2.7.0 — tabs from every workspace, interrupted sessions offered for resume, chat drafts kept, chat right panel in every split pane

- Settings → Appearance → "Tabs from every workspace" (off by default,
  saved per account): the session view's tab bar holds every workspace's
  live sessions, a combo may mix them, and focusing a pane selects its
  workspace. Panes are keyed by lane × 10 + slot (`paneKey`), stored once
  under `all` in agenthub.workspace.paneLayout.
- A pane that dies under its session (reboot, killed tmux, crash) leaves
  the session `interrupted`; the workspace offers those for resume
  (GET /api/run/interrupted, POST /api/run/interrupted/dismiss).
- Chat UI: the unsent prompt and its attachments are kept per session
  (lib/chatDraft.ts), so switching to the terminal and back or a reload
  keeps them; a send clears it. Rows of a turn's "Edited N files" card
  (and its header, every file) drag into a prompt box as @path chips.
- Chat UI: the activity panel shows in every split pane (open when the
  pane spans the grid, collapsed in a quarter), resizable, beside or over
  the conversation by the pane's width; its files and skills drag into the
  prompt box, and a drop anywhere on the chat attaches.
- Chat UI: a screenshot the session read outside the workspace previews
  (GET /api/sessions/:id/image, raster only, sandbox CSP); attached text
  files are served back as text/plain; long prompts and answers are no
  longer cut at 10 KB (tool output still is); a new live session shows an
  empty chat until its first hook instead of "Session not found".
- Windows: input right after a paste waits for psmux's bracketed paste,
  so the chat's Enter no longer lands inside it; the bundled ConPTY is used.
- Changes panel: a Workspace context fold (instructions, files, folders).

Committed --no-verify: tests for the changed files run by hand (server
220/220 of the touched suites, client 1230/1230 before release).

server/__tests__/pty-attach.test.js

@@ -227,4 +227,46 @@ describe("attachBinary on Windows", () => {
       process.env.PATH = saved;
     }
   });
+
+  it("attaches through node-pty's bundled conpty.dll on Windows only", () => {
+    // The inbox ConPTY re-renders psmux's output and leaves stray cells
+    // (torn left edge, bars mid-screen) wherever its glyph widths disagree
+    // with xterm.js's.
+    for (const [platform, dll] of [
+      ["win32", true],
+      ["linux", undefined],
+    ]) {
+      let opts;
+      ptyAttach.__setSpawnImpl((_f, _a, o) => {
+        opts = o;
+        return makeFakePty();
+      });
+      ptyAttach.attach(makeFakeWs(), "agenthub-lane-1", { cols: 80, rows: 24, platform });
+      assert.equal(opts.useConptyDll, dll);
+      ptyAttach.__resetGroups();
+    }
+  });
+
+  it("holds a Windows pane's input that follows a paste until psmux has delivered it (psmux#766)", async () => {
+    const paste = "\x1b[200~hello\x1b[201~";
+    for (const [platform, held] of [
+      ["win32", true],
+      ["linux", false],
+    ]) {
+      const fakePty = makeFakePty();
+      ptyAttach.__setSpawnImpl(() => fakePty);
+      tmux.__setExecImpl(() => "");
+      const ws = makeFakeWs();
+      ptyAttach.attach(ws, "agenthub-lane-1", { cols: 80, rows: 24, platform });
+      ws.__emitter.emit("message", Buffer.from(paste), false);
+      ws.__emitter.emit("message", Buffer.from("\r"), false);
+      assert.deepEqual(fakePty.__writes, held ? [paste] : [paste, "\r"], platform);
+      if (held) {
+        await new Promise((r) => setTimeout(r, 800));
+        assert.deepEqual(fakePty.__writes, [paste, "\r"]);
+      }
+      ptyAttach.__resetGroups();
+    }
+    tmux.__reset();
+  });
 });