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/lib/lanes.js

@@ -138,6 +138,28 @@ function hydrate(row) {
   return { ...row, stages, links, ports };
 }
 
+/**
+ * A lane's display name, as a column value. The title column is NOT NULL TEXT
+ * and the dashboard's rename field writes it straight through, so it is
+ * trimmed and capped — a pasted file is not a lane name. `null` clears the
+ * title rather than violating the NOT NULL, because clearing is legitimate:
+ * every render is `lane.title || lane.cwd`. A non-scalar is bad input and is
+ * rejected the same way every other patch value is (see `bindable`).
+ *
+ * @param {unknown} value - Whatever the caller offered as a title.
+ * @returns {string} A safe column value.
+ * @throws {Error} code `EBADFIELD` when the value is not a scalar.
+ */
+const TITLE_MAX = 200;
+function normalizeTitle(value) {
+  if (value === null || value === undefined) return "";
+  const t = typeof value;
+  if (t !== "string" && t !== "number" && t !== "bigint") {
+    throw Object.assign(new Error("title must be a string"), { code: "EBADFIELD" });
+  }
+  return String(value).trim().slice(0, TITLE_MAX);
+}
+
 function createLane({
   title = "",
   cwd,
@@ -161,7 +183,7 @@ function createLane({
       "INSERT INTO lanes (title, cwd, branch, pipeline, kind, source_repo, base_branch, slug, tool, router_profile, stage_since) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)"
     )
     .run(
-      title,
+      normalizeTitle(title),
       cwd.replace(/\/+$/, ""),
       branch,
       pipeline,
@@ -184,6 +206,31 @@ function getLane(id) {
   return hydrate(db.prepare("SELECT * FROM lanes WHERE id = ?").get(id));
 }
 
+/**
+ * A patch value, as something better-sqlite3 will actually bind.
+ *
+ * It binds numbers, strings, bigints, buffers and null — and THROWS on
+ * anything else, including the `true` and the `{}` a hand-rolled PATCH can
+ * send for any free-text lane column. That throw is indistinguishable from a
+ * server fault by the time it reaches Express, so the route answered 500 to
+ * what is plainly bad input. Rejecting here gives every PATCHABLE field the
+ * one rule, rather than a special case per field the UI happens to expose.
+ *
+ * @param {string} key - The column being patched, for the error message.
+ * @param {unknown} value - Whatever the caller sent for it.
+ * @returns {string|number|bigint|null} A bindable value.
+ * @throws {Error} code `EBADFIELD` when the value is not a scalar.
+ */
+function bindable(key, value) {
+  if (key === "title") return normalizeTitle(value);
+  if (value === null || value === undefined) return null;
+  const t = typeof value;
+  if (t === "string" || t === "number" || t === "bigint") return value;
+  throw Object.assign(new Error(`${key} must be a string, a number or null`), {
+    code: "EBADFIELD",
+  });
+}
+
 function updateLane(id, patch = {}) {
   // Validate kind before building the UPDATE if it's being set
   if ("kind" in patch && patch.kind !== null && patch.kind !== undefined) {
@@ -197,7 +244,8 @@ function updateLane(id, patch = {}) {
   for (const [k, v] of Object.entries(patch)) {
     if (!PATCHABLE.has(k)) continue;
     cols.push(`${k} = ?`);
-    vals.push(k === "links" && typeof v === "object" ? JSON.stringify(v) : v);
+    if (k === "links" && v !== null && typeof v === "object") vals.push(JSON.stringify(v));
+    else vals.push(bindable(k, v));
   }
   if (cols.length) {
     cols.push("updated_at = ?");