An N running subagents badge opens a list of the agent's subagents, each a
link to its terminal, so you can switch without going back to the agents page.
A subagent counts as running when it published a row in the last 15 minutes;
the quiet ones are listed below it, dimmed. The list under the preview and the
menu now share one fetch hook and one definition of running.
The agent's turn-state header ($SWARM.agent-state.<agent>) gains
`needs_login`, set by hive-agent from its own LoginState, so the flag
reaches the swarm without hive-c0re (mara on #5268: "id prefer the agent
container sending the info it needs login without hive").
- swarm-queue-client: `agent_login::Login`, the shared wire type, beside
`agent_inference::Effective`. `needs_login: Option<bool>` with
`#[serde(default)]`: a header from an older agent decodes as `None`
(unknown), never as "needs login" or "logged in".
- hive-agent: the header publisher reads the shared LoginState cell.
Every writer of that cell emits a status on the bus afterwards, so a
login change goes out on the next rebuild, not the 60 s refresh.
- swarm-controller: `agent_login::Reported` follows every agent's header
and keeps the latest flag; `GET /api/agents/status` merges it into each
row as `needs_login` (null when unknown).
- swarm-ui: AgentCard shows a warning-tone "login needed" badge when the
row's `needs_login` is true.
Refs #5268
pages/agents held the roster page, the terminal page and every component under them. It keeps the two pages; the components move to src/agent, by concern: roster (card, wanted menu, actions), detail (panel body, dialog, inference, linked accounts, link menu) and terminal (preview, input, subagents, stream hooks, favicon), with the shared row type and icon at the top. Moves and import rewrites only.
