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.

hive-agent/src/main.rs

@@ -36,6 +36,7 @@ mod swarm_agent_icon;
 mod swarm_agent_state;
 mod swarm_inference;
 mod swarm_input;
+mod swarm_permissions;
 mod swarm_queue;
 mod swarm_term;
 mod term_msg;
@@ -496,6 +497,8 @@ async fn serve_main<S: Surface>(socket: &Path, poll_ms: u64) -> Result<()> {
     swarm_agent_icon::spawn();
     // The model and effort the swarm sets for this agent, over its local ones.
     tokio::spawn(swarm_inference::run(bus.clone()));
+    // The permissions the swarm grants this agent, read before each turn.
+    tokio::spawn(swarm_permissions::run());
     // Set by the web UI's `/api/cancel` on a successful SIGINT, read-and-
     // cleared by `handle_turn` before building the next wake prompt — see
     // `hive_sh4re::inbox::INTERRUPTED_HINT`. Shared between the web server task and