swarm-ui: make agent creation a five-step dialog with a fixed header and footer

The create dialog was one tall form that scrolled as a whole, so its header
and button moved out of view. It is now steps you go through in order:
identity, instructions (AGENTS.md in a box of its own), permissions,
resources and inference, then a summary of what will be sent and what the
agent creation queues, where create is. The header, step tabs and footer stay
put and only the step's own fields scroll. A refused AGENTS.md text sends the
dialog back to its step. The request is unchanged.

frontend/packages/swarm-ui/test/create-agent-steps.test.mjs

@@ -0,0 +1,101 @@
+// The create-agent dialog's steps: order, what gates next, and the summary.
+// Run by `npm test` with Node's type stripping.
+import assert from "node:assert/strict";
+import { test } from "node:test";
+import {
+  nameProblem,
+  nextStep,
+  previousStep,
+  STEPS,
+  stepProblem,
+  summaryRows,
+} from "../src/pages/CreateAgentSteps.ts";
+
+const ready = {
+  name: "ruth",
+  hive: "h1",
+  permissionsReady: true,
+  inferenceProblem: null,
+};
+
+test("the steps run in order and stop at both ends", () => {
+  assert.deepEqual(STEPS, [
+    "identity",
+    "instructions",
+    "permissions",
+    "resources",
+    "summary",
+  ]);
+  assert.equal(nextStep("identity"), "instructions");
+  assert.equal(nextStep("resources"), "summary");
+  assert.equal(nextStep("summary"), "summary");
+  assert.equal(previousStep("summary"), "resources");
+  assert.equal(previousStep("identity"), "identity");
+});
+
+test("a name is 1-63 lowercase letters, digits and hyphens", () => {
+  assert.equal(nameProblem("ruth-2"), null);
+  assert.equal(nameProblem("a".repeat(63)), null);
+  assert.notEqual(nameProblem(""), null);
+  assert.notEqual(nameProblem("a".repeat(64)), null);
+  assert.notEqual(nameProblem("Ruth"), null);
+  assert.notEqual(nameProblem("ru th"), null);
+});
+
+test("identity needs a valid name and a hive before next", () => {
+  assert.equal(stepProblem("identity", ready), null);
+  assert.notEqual(stepProblem("identity", { ...ready, name: "" }), null);
+  assert.notEqual(stepProblem("identity", { ...ready, name: "No Way" }), null);
+  assert.equal(stepProblem("identity", { ...ready, hive: "" }), "pick a hive");
+});
+
+test("permissions waits for the list, resources for a valid inference", () => {
+  assert.notEqual(
+    stepProblem("permissions", { ...ready, permissionsReady: false }),
+    null,
+  );
+  assert.equal(stepProblem("permissions", ready), null);
+  assert.equal(
+    stepProblem("resources", { ...ready, inferenceProblem: "bad model" }),
+    "bad model",
+  );
+  assert.equal(stepProblem("instructions", { ...ready, name: "" }), null);
+});
+
+test("the summary lists what is sent and what stays at its default", () => {
+  const rows = (over) =>
+    Object.fromEntries(
+      summaryRows({
+        name: "ruth",
+        hive: "h1",
+        archetype: undefined,
+        permissions: undefined,
+        caps: {},
+        inference: {},
+        agentsMd: "",
+        ...over,
+      }).map((r) => [r.label, r.value]),
+    );
+  const plain = rows({});
+  assert.equal(plain.name, "ruth");
+  assert.equal(plain.archetype, "none: a custom agent");
+  assert.equal(plain.permissions, "the default set");
+  assert.equal(plain["resource caps"], "none set");
+  assert.equal(plain.inference, "none set");
+  assert.equal(plain.instructions, "none");
+
+  const set = rows({
+    archetype: "reviewer",
+    permissions: ["meta", "inbox"],
+    caps: { cpu_quota: "200%", memory_max: "2G" },
+    inference: { model: "opus", subagent_models: ["haiku", "sonnet"] },
+    agentsMd: "  Be   brief.\n",
+  });
+  assert.equal(set.archetype, "reviewer");
+  assert.equal(set.permissions, "meta, inbox");
+  assert.equal(set["resource caps"], "cpu quota 200%; memory max 2G");
+  assert.equal(set.inference, "model opus; subagent models haiku, sonnet");
+  assert.equal(set.instructions, "AGENTS.md, 2 words");
+  assert.equal(rows({ permissions: [] }).permissions, "none");
+  assert.equal(rows({ agentsMd: "x" }).instructions, "AGENTS.md, 1 word");
+});