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).

client/src/components/settings/AppearanceSettings.tsx

@@ -1,7 +1,9 @@
 /**
  * @file AppearanceSettings.tsx
  * @description Settings → Appearance (`/settings/appearance`): the per-user
- * Chat UI default (`ChatUiSettings`, `#chat-ui`), the interface language, the
+ * Chat UI default (`ChatUiSettings`, `#chat-ui`), whether the session view's
+ * tabs hold every workspace's sessions (`lib/workspaceTabs.ts`,
+ * `#workspace-tabs`), the interface language, the
  * terminal font (`lib/terminalFont.ts`, with a preview line), the
  * Dark / Light / System mode switch and one named-theme picker per mode, and the
  * corner pet (`PetSettings`, deep-linked as `#pet`) — the old General and Pet
@@ -17,7 +19,7 @@
 import { useState } from "react";
 import { useTranslation } from "react-i18next";
 import { Monitor, Moon, RotateCcw, Sun } from "lucide-react";
-import { SettingsRow, SettingsSection, SettingsSegmented } from "./SettingsRow";
+import { SettingsRow, SettingsSection, SettingsSegmented, SettingsSwitchRow } from "./SettingsRow";
 import { PetSettings } from "./PetSettings";
 import { ChatUiSettings } from "./ChatUiSettings";
 import { Select } from "../Select";
@@ -31,6 +33,7 @@ import {
   writeTerminalFont,
   type TerminalFont,
 } from "../../lib/terminalFont";
+import { readAllTabs, writeAllTabs } from "../../lib/workspaceTabs";
 
 export const THEME_LABELS: Record<string, string> = {
   darcula: "Darcula",
@@ -79,6 +82,7 @@ export function AppearanceSettings() {
   const { t, i18n } = useTranslation("settings");
   const { mode, theme, themeFor, setMode, setThemeFor } = useTheme();
   const [termFont, setTermFont] = useState(readTerminalFont);
+  const [allTabs, setAllTabs] = useState(readAllTabs);
   const pickTermFont = (font: TerminalFont) => {
     writeTerminalFont(font);
     setTermFont(font);
@@ -101,6 +105,22 @@ export function AppearanceSettings() {
     <div className="space-y-6">
       <ChatUiSettings />
 
+      <SettingsSection
+        id="workspace-tabs"
+        title={t("workspaceTabs.title")}
+        description={t("workspaceTabs.description")}
+      >
+        <SettingsSwitchRow
+          label={t("workspaceTabs.label")}
+          description={t("workspaceTabs.labelDesc")}
+          checked={allTabs}
+          onChange={(on) => {
+            writeAllTabs(on);
+            setAllTabs(on);
+          }}
+        />
+      </SettingsSection>
+
       <SettingsSection
         id="language"
         title={t("language.title")}