feat(workspace): a session in its own worktree, Claude's way

Desktop-parity phase 6, following Claude Desktop:
- the workspace home's Worktree checkbox starts the pane with
  `claude --worktree=<name>`, so Claude Code makes, populates
  (.worktreeinclude, WorktreeCreate hook) and cleans up
  <repo>/.claude/worktrees/<name>; AgentHub only excludes
  /.claude/worktrees/ at the repo root (Claude does not)
- server/lib/session-worktree.js resolves a session's worktree from the
  session row only (owned by the workspace, registered by git worktree
  list); every lane git route takes ?session= and answers ENOWORKTREE
  instead of falling back to the main folder
- the session view's Changes panel works in the opened run's worktree
  (dashboard_runs.worktree, GitTarget in the client api)
- Resume/Fork start in the session's worktree; a gone one is ENOWORKTREE
- Archive of a worktree session removes the worktree after asking:
  git worktree remove without --force, git branch -d (unmerged work keeps
  its branch), a lock held by a live pid refused, a stale one cleared
- listWorktrees reads `locked <reason>` locks
- tests scrub GIT_* env so the pre-commit suite cannot act on this repo

client/src/lib/__tests__/gitTargetApi.test.ts

@@ -0,0 +1,39 @@
+/**
+ * @file Pins where a workspace git call goes: the workspace's own routes, or —
+ * for a session's worktree target — the same routes with `?session=`, which
+ * the server resolves to that session's worktree.
+ * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
+ */
+
+import { describe, it, expect, vi, afterEach } from "vitest";
+import { api, gitTarget } from "../api";
+
+afterEach(() => {
+  vi.unstubAllGlobals();
+});
+
+function stubFetch() {
+  const spy = vi.fn().mockResolvedValue({
+    ok: true,
+    status: 200,
+    headers: { get: () => "application/json" },
+    json: async () => ({}),
+  });
+  vi.stubGlobal("fetch", spy);
+  return spy;
+}
+
+describe("git targets", () => {
+  it("adds session= for a worktree target and nothing for the workspace", async () => {
+    const spy = stubFetch();
+    await api.lanes.changes(3, { range: "work" });
+    await api.lanes.changes(gitTarget(3, "s-1"), { range: "work" });
+    await api.lanes.gitAction(gitTarget(3, "s-1"), "stage", { paths: ["a"] });
+    await api.lanes.git(gitTarget(3, null));
+    const urls = spy.mock.calls.map((c) => String(c[0]));
+    expect(urls[0]).toMatch(/\/lanes\/3\/git\/changes\?range=work$/);
+    expect(urls[1]).toMatch(/\/lanes\/3\/git\/changes\?range=work&session=s-1$/);
+    expect(urls[2]).toMatch(/\/lanes\/3\/git\/stage\?session=s-1$/);
+    expect(urls[3]).toMatch(/\/lanes\/3\/git$/);
+  });
+});