Remote agents show as online and offer only Shutdown after their process exits, with no UI path to redeploy

**Describe the bug**

A remote (provider-backed) agent whose process is dead still shows as **online** in its profile panel, and its primary action button stays **Shutdown** — so there is no way to bring it back from the UI. The same agent correctly shows as **offline** in the channel members sidebar at the same moment.

Root cause is one shared source-of-truth mistake in two places:

1. `desktop/src/features/profile/ui/UserProfilePanelSections.tsx:192-198` — for a bot with a managed agent, the real `presenceStatus` is discarded and the avatar dot is derived from `isManagedAgentActive(managedAgent)` instead.
2. `desktop/src/features/agents/lib/managedAgentControlActions.ts:34-41` — the primary action label uses the same helper.

`isManagedAgentActive` is `status === "running" || status === "deployed"`, and for remote agents `status` comes from `record.backend_agent_id.is_some()` (`desktop/src-tauri/src/managed_agents/runtime.rs:163-168`), which is never cleared. So a provider agent is `deployed` forever, regardless of whether the process is alive.

By contrast `desktop/src/features/channels/ui/MembersSidebarMemberCard.tsx:169-174` renders `PresenceDot` from the real relay presence — hence the contradiction between the two views.

Note the two-axis model itself is fine and documented (`runtime.rs:145-163`, `docs/remote-agents.md:461`): `status` = "does infrastructure exist", presence = "is the harness connected". The bug is that the UI reads the infrastructure axis where it needs the liveness axis.

**Steps to reproduce**

1. Create a remote agent on a provider backend (reproduced with the Kubernetes backend).
2. Let the agent exit — e.g. wait out `BUZZ_ACP_EXIT_AFTER_INACTIVITY` (default 7200s, `crates/buzz-backend-kubernetes/src/config.rs:35`), so the pod completes (`restartPolicy: Never`).
3. Look at the agent in the channel members sidebar → shows **offline** (correct).
4. Open the agent's profile panel → avatar shows **online**, and the primary button reads **Shutdown**.
5. There is no UI path to redeploy it.

**Expected behavior**

For provider-backed agents, both the profile avatar dot and the primary action should follow relay presence: offline agent → offline dot → **Deploy** button. `deploy` is already idempotent and normatively converges on a live instance (`docs/remote-agents.md:875-879`; the Kubernetes binding replaces a terminated pod — see `terminated_pod_is_replaced_with_a_fenced_delete` in `crates/buzz-backend-kubernetes/src/reconcile.rs:849`), so pressing Deploy would just work. Only the gating condition is wrong.

**Version and platform**

- Buzz version: 0.5.11 (code path verified unchanged in `main` @ `69107dc3b`)
- OS: macOS

**Additional context**

This currently blocks practical use of the Kubernetes provider: any agent that idles out is unreachable from the UI until the user edits `managed-agents.json` by hand to null out `backend_agent_id`.

Related but larger: it would be better still if mentioning an offline provider-backed agent redeployed it automatically, rather than requiring a manual button press. Happy to file that separately if it's wanted.