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-mcp/src/mcp/mod.rs

@@ -11,7 +11,7 @@
 //!
 //! One `AgentServer { socket }` struct for all roles.
 //! Tool access is gated upstream by `--allowedTools` (derived from the
-//! agent's `ToolGroup` config); the server itself is a dumb dispatcher.
+//! agent's `Permission` set); the server itself is a dumb dispatcher.
 //! All tools go through the same `run_tool_envelope` helper.
 
 use std::future::Future;
@@ -135,7 +135,7 @@ impl AgentServer {
 }
 
 // IMPORTANT: when adding a new `#[tool]` fn to this impl, also add
-// its name to the matching `ToolGroup::tools()` slice in hive-sh4re.
+// its name to the matching `Permission::tools()` slice in hive-sh4re.
 // Claude Code's permission gate refuses uninlisted MCP tools in
 // non-interactive `--print` mode with "permissions not granted yet".
 #[tool_router]