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.

server/__tests__/lanes-lib.test.js

@@ -358,6 +358,48 @@ describe("lanes lib", () => {
     assert.equal(after.tool, "codex");
     assert.equal(after.title, "x");
   });
+
+  // The Workspace's inline rename PATCHes `title` straight from a text field,
+  // so the column is now reachable by anything same-origin. A non-string would
+  // reach better-sqlite3 as a datatype throw and surface as a 500 on what is
+  // plain bad input.
+  it("normalizes a title on create and on update", () => {
+    const lane = lanes.createLane({ cwd: "/tmp/title-norm", title: "  spaced  " });
+    assert.equal(lane.title, "spaced");
+    assert.equal(lanes.updateLane(lane.id, { title: 42 }).title, "42");
+    assert.equal(lanes.updateLane(lane.id, { title: "x".repeat(500) }).title.length, 200);
+    // null clears rather than violating the NOT NULL, and the empty string is
+    // a real value: it puts the lane's cwd back in the UI's place for it.
+    assert.equal(lanes.updateLane(lane.id, { title: null }).title, "");
+    assert.equal(lanes.updateLane(lane.id, { title: "" }).title, "");
+  });
+
+  // Every free-text column, not just the one the rename field exposes: a
+  // non-scalar reaches better-sqlite3 as a datatype throw, which Express can
+  // only report as a 500 on what is plainly the caller's mistake.
+  it("rejects a non-scalar patch value on any patchable column", () => {
+    const lane = lanes.createLane({ cwd: "/tmp/patch-scalar" });
+    for (const patch of [
+      { title: { evil: true } },
+      { notes: { a: 1 } },
+      { branch: ["main"] },
+      { ci_status: true },
+      { session_id: () => "x" },
+    ]) {
+      assert.throws(
+        () => lanes.updateLane(lane.id, patch),
+        (err) => err.code === "EBADFIELD",
+        `expected EBADFIELD for ${JSON.stringify(Object.keys(patch))}`
+      );
+    }
+    assert.throws(
+      () => lanes.createLane({ cwd: "/tmp/patch-scalar-create", title: { evil: true } }),
+      (err) => err.code === "EBADFIELD"
+    );
+    // `links` is the one patchable column that IS an object — it is stored as
+    // JSON, so it must keep working.
+    assert.deepEqual(lanes.updateLane(lane.id, { links: { pr: "u" } }).links, { pr: "u" });
+  });
 });
 
 const { withLaneLock } = require("../lib/lane-lock");