agent permissions: one set, tool groups included, set at agent creation

mara on #5170: "dont split caps and perms. its all perms. / dont include
the now empty tool groups / nothing set -> default / also add perms to
agent creation screen".

- hive-sh4re: one `Permission` enum (messaging, meta, inbox, execution,
  web_tools, manage_root_agent) replaces `ToolGroup` and `Capability`;
  `lifecycle`/`forge` are gone. `Permission::default_for` is the default
  for an agent the swarm sets nothing for.
- The record is `{ "permissions": [...] }`. Missing key, unset field or
  no successful read yet = default; `[]` = none; a failed read after a
  good one keeps the last value.
- hive-agent reads its own key every 10s and builds each turn's --tools,
  --allowedTools and MCP config (rewritten before every turn) from it;
  the subagent daemon reads it on each start/continue. Agents get a
  read-only grant on their own key.
- hive-c0re restarts an agent only when its manage_root_agent changes.
  The import now merges meta/capabilities.json and meta/tool-groups.json
  into one list per agent and deletes both; the "import pending, don't
  read" decision is `ImportOutcome::read_allowed`, table-tested.
- swarm-controller: `GET /api/permissions` (names + default) and an
  optional `permissions` on `POST /api/agents`, stored before the job is
  queued. swarm-ui's create-agent form gets a permissions field.
- Deleted: HIVE_TOOL_GROUPS and its forward to the subagent daemon,
  tool_groups.rs, ruth's tool-group seed, the permissions rebuild job
  (PermPayload/WritePermFile/perm_change), the dashboard permissions tab
  and its stale-entries panel.

Part of #5170.

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

@@ -0,0 +1,31 @@
+// The create-agent form's permissions field: what a toggle does and what the
+// create request carries. Run by `npm test` with Node's type stripping.
+import assert from "node:assert/strict";
+import { test } from "node:test";
+import {
+  requestPermissions,
+  togglePermission,
+} from "../src/pages/CreateAgentPermissions.ts";
+
+const defaults = ["messaging", "meta", "inbox", "execution"];
+
+test("a toggle adds a missing permission and removes a present one", () => {
+  assert.deepEqual(togglePermission(["meta"], "inbox"), ["meta", "inbox"]);
+  assert.deepEqual(togglePermission(["meta", "inbox"], "meta"), ["inbox"]);
+});
+
+test("the default set, in any order, sends no permissions", () => {
+  assert.equal(
+    requestPermissions([...defaults].reverse(), defaults),
+    undefined,
+  );
+});
+
+test("a changed set is sent, an empty one included", () => {
+  assert.deepEqual(requestPermissions(["messaging"], defaults), ["messaging"]);
+  assert.deepEqual(requestPermissions([], defaults), []);
+  assert.deepEqual(requestPermissions([...defaults, "web_tools"], defaults), [
+    ...defaults,
+    "web_tools",
+  ]);
+});