feat(lanes): reorder and rename lane cards, and show each file's line delta

The lane strip's tiles are now drag-reorderable (Alt+←/→ is the keyboard
path), and a lane's name can be set in place from the detail header. The
"Lane 23 ·" prefix is gone from both — the bare `#23` stays on the tile,
because that number is how the CLI addresses a lane.

Card order is a per-viewer preference, not a lane fact: it lives in
localStorage (`agenthub.workspace.laneOrder`) beside the split-view layout
and writes nothing server-side, so `GET /api/lanes` and `agenthub lanes`
keep answering in id order. Renaming is the opposite — it is PATCH
/api/lanes/:id with {title}, the one lane column a user now types into
directly.

That made a patch value reachable by hand for the first time, so
`bindable` now rejects any non-scalar for every PATCHABLE column with
EBADFIELD, and the route answers 400 for that and for the
SQLITE_CONSTRAINT family, rather than handing better-sqlite3 a datatype
throw and reporting 500 on plain bad input.

The uncommitted-files tooltip became a real panel. `GET /api/lanes/:id/git`
now returns `files` as {path, status, added, deleted} records — deltas from
one `git diff --numstat HEAD`, null where git has none to report (untracked,
binary, renamed) — and the card renders them portalled to the body, so the
Workspace's own scroll box cannot clip the list.

client/src/components/lanes/__tests__/LaneCard.test.tsx

@@ -9,7 +9,7 @@
  */
 
 import { describe, it, expect, vi, beforeEach } from "vitest";
-import { render, screen, waitFor } from "@testing-library/react";
+import { render, screen, waitFor, fireEvent } from "@testing-library/react";
 import userEvent from "@testing-library/user-event";
 import LaneCard, { LaneToolsMenu, LaneRouterRow } from "../LaneCard";
 import type { Lane, LaneRuntime } from "../../../lib/types";
@@ -207,7 +207,11 @@ describe("LaneCard git block", () => {
     subject: "free-text rule mode in the form",
     dirty: 2,
     untracked: 1,
-    files: [" M server/lib/alerts.js", " M client/src/lib/api.ts", "?? scratch.txt"],
+    files: [
+      { path: "server/lib/alerts.js", status: " M", added: 12, deleted: 3 },
+      { path: "client/src/lib/api.ts", status: "M ", added: 1, deleted: 0 },
+      { path: "scratch.txt", status: "??", added: null, deleted: null },
+    ],
   };
 
   it("renders the live branch, head, subject and uncommitted counts", async () => {
@@ -219,14 +223,61 @@ describe("LaneCard git block", () => {
     expect(block.textContent).toContain("9b3e74a");
     expect(block.textContent).toContain("free-text rule mode in the form");
     expect(block.textContent).toContain("2");
-    // Hovering the counts names the files behind them.
-    expect(screen.getByText(/modified/).title).toBe(
-      " M server/lib/alerts.js\n M client/src/lib/api.ts\n?? scratch.txt"
-    );
     // The live branch replaces the lane's recorded one rather than doubling it.
     expect(screen.queryByText(/stale\/recorded/)).toBeNull();
   });
 
+  it("names the files behind the counts on hover, with each one's line delta", async () => {
+    vi.mocked(api.lanes.git).mockResolvedValueOnce(facts);
+    render(<LaneCard lane={makeLane()} onAction={vi.fn()} />);
+
+    const counts = await screen.findByTestId("lane-git-counts");
+    // Hidden until asked for: the row is a one-line summary until you hover.
+    expect(screen.queryByTestId("lane-git-files")).toBeNull();
+
+    fireEvent.mouseEnter(counts);
+    const panel = screen.getByTestId("lane-git-files");
+    expect(panel.textContent).toContain("alerts.js");
+    expect(panel.textContent).toContain("+12");
+    expect(panel.textContent).toContain("−3");
+    // Totals across the listed files.
+    expect(panel.textContent).toContain("+13");
+    // An untracked file has no delta to report and says so rather than "+0".
+    expect(panel.textContent).toContain("new");
+    expect(panel.textContent).toContain("3 files changed");
+
+    // Closing is delayed so the pointer can travel into the panel and scroll
+    // it — the panel is portalled to the body, away from its trigger.
+    fireEvent.mouseLeave(counts);
+    expect(screen.queryByTestId("lane-git-files")).not.toBeNull();
+    await waitFor(() => expect(screen.queryByTestId("lane-git-files")).toBeNull());
+  });
+
+  it("stays open while the pointer is inside the panel", async () => {
+    vi.mocked(api.lanes.git).mockResolvedValueOnce(facts);
+    render(<LaneCard lane={makeLane()} onAction={vi.fn()} />);
+
+    const counts = await screen.findByTestId("lane-git-counts");
+    fireEvent.mouseEnter(counts);
+    fireEvent.mouseLeave(counts);
+    // The pointer landed on the panel before the pending close fired.
+    fireEvent.mouseEnter(screen.getByTestId("lane-git-files"));
+    await new Promise((r) => setTimeout(r, 200));
+    expect(screen.queryByTestId("lane-git-files")).not.toBeNull();
+
+    fireEvent.mouseLeave(screen.getByTestId("lane-git-files"));
+    await waitFor(() => expect(screen.queryByTestId("lane-git-files")).toBeNull());
+  });
+
+  it("says how many files the server-side cap left out", async () => {
+    // 40 uncommitted files, 3 listed: the counts are exact, the listing is not.
+    vi.mocked(api.lanes.git).mockResolvedValueOnce({ ...facts, dirty: 39, untracked: 1 });
+    render(<LaneCard lane={makeLane()} onAction={vi.fn()} />);
+
+    fireEvent.mouseEnter(await screen.findByTestId("lane-git-counts"));
+    expect(screen.getByTestId("lane-git-files").textContent).toContain("37 more");
+  });
+
   it("omits the uncommitted line when the tree is clean", async () => {
     vi.mocked(api.lanes.git).mockResolvedValueOnce({ ...facts, dirty: 0, untracked: 0 });
     render(<LaneCard lane={makeLane()} onAction={vi.fn()} />);