feat(nodes): SSH bootstrap + housekeeping — install script, bundled binaries, auto-prune (#50)

* feat(nodes): SSH bootstrap + housekeeping — install script, bundled binaries, auto-prune

- `containr nodes add <user@host>` mints an enroll token, SSHes once,
  runs the install script remotely; --print emits the one-liner
- Public /api/agents/install.sh + /api/agents/download/{platform};
  agent binaries built into the image under /agents
- Agent-side `prune` (bounded docker system prune, volumes opt-in)
  and `system_df` commands
- node_agents.auto_prune + health sweep enqueues daily prune;
  offline/online transitions notify admins
- CLI nodes update/prune/commands + MCP tools (prune confirm-gated)
- Usage page: install one-liner, per-node Prune + auto toggle

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

* feat(nodes): node detail page — telemetry, containers, commands, controls

/nodes/:id (admin): cpu/mem sparklines from heartbeat history
(1h/24h/7d), containers on node, command history, inline rename,
auto-prune toggle, prune-now with volume opt-in, remove. Agent rows
on the Usage page link into it.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

* feat(nodes): mesh awareness + node detail page

- agent reports tailscale/netbird/zerotier/wireguard interface IPs at
  register (authoritative — absent interfaces clear stored state)
- backend stores under node_agents.metadata.mesh, merged on re-register
- node detail page shows mesh addresses under the primary IP

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

---------

Co-authored-by: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

app/backend/sqlc/queries/agents.sql

@@ -28,6 +28,7 @@ UPDATE node_agents SET
     resources = $9,
     last_heartbeat = $10,
     metadata = $11,
+    auto_prune = $12,
     updated_at = NOW()
 WHERE id = $1
 RETURNING *;
@@ -107,3 +108,8 @@ RETURNING *;
 -- name: UpdateContainerStatus :exec
 UPDATE container_instances SET status = $2, updated_at = NOW()
 WHERE id = $1;
+
+-- name: GetLastAgentCommandByType :one
+SELECT * FROM agent_commands
+WHERE node_agent_id = $1 AND type = $2
+ORDER BY created_at DESC LIMIT 1;