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-c0re/src/agent_config/capabilities.rs

@@ -1,109 +0,0 @@
-//! The capabilities the swarm grants this hive's agents, as last read from the
-//! `agent-permissions` bucket by `workers::swarm_permissions`. Stored at
-//! `/var/lib/hyperhive/swarm-agent-permissions.json`, outside the meta repo:
-//! the swarm is the record, this file is the hive's last read of it.
-//!
-//! Format: agent name → the stored
-//! [`swarm_queue_client::agent_permissions::AgentPermissions`]. An agent with
-//! no entry, or an entry with `capabilities` unset, holds its default
-//! ([`default_for`]); `"capabilities": []` holds none.
-//!
-//! Read path: `lifecycle::host_config::set_nspawn_flags`, on every container
-//! start, which is why a change takes a restart.
-
-use std::collections::BTreeMap;
-use std::path::{Path, PathBuf};
-
-use hive_sh4re::permissions::Capability;
-use swarm_queue_client::agent_permissions::AgentPermissions;
-
-const FILE: &str = "swarm-agent-permissions.json";
-
-pub type Stored = BTreeMap<String, AgentPermissions>;
-
-#[must_use]
-pub fn path() -> PathBuf {
-    crate::paths::state_root().join(FILE)
-}
-
-/// Read the stored permissions. An absent file is the empty map: every agent
-/// on its default. A file that exists but can't be read or parsed is an error.
-pub fn read_at(path: &Path) -> std::io::Result<Stored> {
-    super::read_map(path)
-}
-
-/// Persist the permissions atomically.
-pub fn write_at(path: &Path, stored: &Stored) -> std::io::Result<()> {
-    super::write_map(path, stored)
-}
-
-/// The capabilities an agent holds when the swarm sets none: `ruth` recovers
-/// the other agents, every other agent holds nothing.
-#[must_use]
-pub fn default_for(agent: &str) -> Vec<Capability> {
-    if agent == crate::lifecycle::MANAGER_NAME {
-        vec![Capability::ManageRootAgent]
-    } else {
-        Vec::new()
-    }
-}
-
-/// The capabilities `agent` holds under `record`.
-#[must_use]
-pub fn effective(agent: &str, record: Option<&AgentPermissions>) -> Vec<Capability> {
-    record
-        .and_then(|r| r.capabilities.clone())
-        .unwrap_or_else(|| default_for(agent))
-}
-
-/// Whether `agent` holds `cap` per the file at `path` (normally [`path`]).
-///
-/// # Errors
-///
-/// As [`read_at`].
-pub fn holds(path: &Path, agent: &str, cap: Capability) -> std::io::Result<bool> {
-    Ok(effective(agent, read_at(path)?.get(agent)).contains(&cap))
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    fn record(json: &str) -> AgentPermissions {
-        serde_json::from_str(json).expect("decodes")
-    }
-
-    #[test]
-    fn unset_is_the_default_and_an_empty_list_is_none() {
-        assert_eq!(effective("ruth", None), vec![Capability::ManageRootAgent]);
-        assert_eq!(
-            effective("ruth", Some(&record("{}"))),
-            vec![Capability::ManageRootAgent]
-        );
-        assert!(effective("ruth", Some(&record(r#"{"capabilities":[]}"#))).is_empty());
-        assert!(effective("atlas", None).is_empty());
-        assert_eq!(
-            effective(
-                "atlas",
-                Some(&record(r#"{"capabilities":["manage_root_agent"]}"#))
-            ),
-            vec![Capability::ManageRootAgent]
-        );
-    }
-
-    #[test]
-    fn a_missing_file_holds_the_defaults() {
-        let dir = tempfile::tempdir().expect("tempdir");
-        let path = dir.path().join(FILE);
-        assert!(holds(&path, "ruth", Capability::ManageRootAgent).expect("missing is empty"));
-        assert!(!holds(&path, "atlas", Capability::ManageRootAgent).expect("missing is empty"));
-    }
-
-    #[test]
-    fn a_corrupt_file_is_an_error() {
-        let dir = tempfile::tempdir().expect("tempdir");
-        let path = dir.path().join(FILE);
-        std::fs::write(&path, "{\n  \"ruth\": {\"capabilities\": [\"manage_root_ag").expect("seed");
-        holds(&path, "ruth", Capability::ManageRootAgent).expect_err("truncated JSON");
-    }
-}