feat: workspaces own their sessions; desktop parity; sidebar and settings cleanup

Workspace sessions (docs/plans/desktop-parity, phases 1-5 and 7):
- sessions.lane_id: a workspace lists only the sessions its panes held,
  stamped by bindRunSession (first writer wins, nested `claude -p`
  excluded); GET /api/sessions?lane=&archived=
- session row state dot, double-click rename, archive (sessions.archived_at,
  hides only); the activity bar's duplicate Sessions tab removed
- Fork beside Resume (--fork-session, Claude only), Ctrl/Cmd+click a live
  session opens it in a second pane, a diff line's comment is pasted into
  the workspace's last-focused pane (lib/panePaste.ts)

dashboard_runs stability:
- a pane's previous run is archived as <pane>@<started_at> instead of being
  overwritten by INSERT OR REPLACE
- a run is flagged abandoned only once its tmux session is gone, at boot and
  on the run-heal beat (panes outlive a server restart)

UI:
- sidebar: no footer, language or theme block; small collapse button in the
  brand corner; version + update check in the connection details modal, a
  status-bar dot while a release is out; language in Settings -> General
- one Switch component for every switch, the themed Checkbox for every
  checkbox (no native checkboxes)

Also: AI Tools catalog trimmed to 10 built-ins (custom-file prompt modes
tested through fixtures), and the workspace plans under docs/plans/ (the
multi-user server plan lives in the AgentHub-Server repo).

client/src/components/run/TerminalView.tsx

@@ -13,7 +13,9 @@
  * (`lib/terminalTheme.ts`), recoloured live without re-attaching.
  * An image dropped on it is saved on the server (`POST /api/run/drop-image`)
  * and its PATH pasted into the pane — what a local terminal does on a drop,
- * and how `claude` attaches an image.
+ * and how `claude` attaches an image. The pane also registers with
+ * `lib/panePaste.ts`, so a diff-line comment from the Changes panel can be
+ * pasted into whichever of the workspace's panes was focused last.
  * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
  */
 import { useEffect, useMemo, useRef, useState, type DragEvent } from "react";
@@ -25,6 +27,7 @@ import "@xterm/xterm/css/xterm.css";
 import { useTheme } from "../../hooks/useTheme";
 import { terminalThemeFor } from "../../lib/terminalTheme";
 import { api } from "../../lib/api";
+import { notePaneFocus, registerPane } from "../../lib/panePaste";
 
 type DropState = "hint" | "uploading" | "failed" | "imagesOnly";
 const hasFiles = (e: DragEvent) => Array.from(e.dataTransfer.types).includes("Files");
@@ -291,6 +294,16 @@ export function TerminalView({ runId, wsBaseUrl, onExit }: TerminalViewProps) {
     if (termRef.current) termRef.current.options.theme = palette;
   }, [palette]);
 
+  // Other parts of the page (a diff-line comment) paste into this pane.
+  useEffect(
+    () =>
+      registerPane(runId, (text) => {
+        termRef.current?.paste(text);
+        termRef.current?.focus();
+      }),
+    [runId]
+  );
+
   return (
     <div
       className="relative h-full w-full"
@@ -311,6 +324,7 @@ export function TerminalView({ runId, wsBaseUrl, onExit }: TerminalViewProps) {
         if (dragDepth.current === 0) setDrop((d) => (d === "hint" ? null : d));
       }}
       onDrop={(e) => void onDrop(e)}
+      onFocus={() => notePaneFocus(runId)}
     >
       <div
         ref={containerRef}