swarm-ui: a schedules page, one card per scheduled prompt

/schedules lists the controller's scheduled prompts as cards: name as the
title, the agents it fires for, the message, its cadence and next fire.
Edit turns a card into its own form; pause, resume and remove act in place,
and + schedule opens an empty form. The form sends only what changed, so a
rename never moves the fire times, and warns when the start or the repeat
does. Filters reuse the shared card filter bar.

Adds a TextAreaField to the ui kit, and an upcoming mode on RelativeTime so
a next-fire time reads "in 5m". Needs the controller's /api/schedules
routes.

frontend/packages/swarm-ui/src/ui/text-area-field/TextAreaField.css

@@ -0,0 +1,5 @@
+/* `min-height` from `.ui-form-control` is a single-line floor; a textarea's
+   own `rows` sets its height, so only the resize axis needs saying here. */
+.ui-text-area {
+  resize: vertical;
+}

frontend/packages/swarm-ui/src/ui/text-area-field/TextAreaField.tsx

@@ -0,0 +1,39 @@
+// <TextAreaField> — `TextField`'s multi-line sibling, for free text that
+// runs past one line (a scheduled prompt's body is the motivating caller).
+// Same label chrome and `.ui-form-control` look as the rest of the kit;
+// the box only grows vertically, since a horizontal drag would break out
+// of whatever column the page gave the field.
+import { FormField } from "../form-field/FormField.js";
+import "./TextAreaField.css";
+
+export function TextAreaField({
+  id,
+  label,
+  value,
+  onInput,
+  rows = 4,
+  required,
+  placeholder,
+}: {
+  id: string;
+  label: string;
+  value: string;
+  onInput: (value: string) => void;
+  rows?: number;
+  required?: boolean;
+  placeholder?: string;
+}) {
+  return (
+    <FormField label={label} htmlFor={id}>
+      <textarea
+        id={id}
+        class="ui-form-control ui-text-area"
+        value={value}
+        rows={rows}
+        required={required}
+        placeholder={placeholder}
+        onInput={(e) => onInput((e.target as HTMLTextAreaElement).value)}
+      />
+    </FormField>
+  );
+}