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/RemoteSources.tsx

@@ -57,6 +57,7 @@
  *
  * ----------------------------------------------------------------------------- */
 
+import { Checkbox } from "./Checkbox";
 import { useCallback, useEffect, useState } from "react";
 import { useTranslation } from "react-i18next";
 import {
@@ -544,17 +545,12 @@ export function RemoteSources() {
               </p>
             </div>
           </div>
-          <label className="flex items-center gap-2 cursor-pointer">
-            <input
-              type="checkbox"
-              className="accent-accent"
-              checked={!!form.enabled}
-              onChange={(e) => setForm((f) => ({ ...f, enabled: e.target.checked }))}
-            />
-            <span className="text-sm text-fg-secondary">
-              {t("remoteSources.fieldEnabled", "Sync automatically in the background")}
-            </span>
-          </label>
+          <Checkbox
+            checked={!!form.enabled}
+            onChange={(v) => setForm((f) => ({ ...f, enabled: v }))}
+            label={t("remoteSources.fieldEnabled", "Sync automatically in the background")}
+            labelClassName="text-sm text-fg-secondary"
+          />
           {formError && (
             <div className="text-xs text-status-danger bg-status-danger/10 border border-status-danger/25 rounded-lg px-3 py-2">
               {formError}
@@ -723,22 +719,16 @@ export function RemoteSources() {
                     <p className="text-xs text-fg-secondary mb-2">
                       {t("remoteSources.confirmDelete", "Remove this source?")}
                     </p>
-                    <label className="flex items-center gap-2 mb-3 cursor-pointer">
-                      <input
-                        type="checkbox"
-                        className="accent-red-500"
-                        checked={confirmDelete.purge}
-                        onChange={(e) =>
-                          setConfirmDelete((c) => c && { ...c, purge: e.target.checked })
-                        }
-                      />
-                      <span className="text-xs text-fg-secondary">
-                        {t(
-                          "remoteSources.purgeData",
-                          "Also delete the sessions imported from this source (cannot be undone)"
-                        )}
-                      </span>
-                    </label>
+                    <Checkbox
+                      className="mb-3"
+                      tone="danger"
+                      checked={confirmDelete.purge}
+                      onChange={(v) => setConfirmDelete((c) => c && { ...c, purge: v })}
+                      label={t(
+                        "remoteSources.purgeData",
+                        "Also delete the sessions imported from this source (cannot be undone)"
+                      )}
+                    />
                     <div className="flex items-center gap-2">
                       <button
                         onClick={doDelete}