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>

app/backend/internal/database/sqlcdb/querier.go

@@ -58,6 +58,7 @@ type Querier interface {
 	GetDatabaseServiceByID(ctx context.Context, id string) (DatabaseService, error)
 	GetDatabaseServiceByIDAndUser(ctx context.Context, arg GetDatabaseServiceByIDAndUserParams) (DatabaseService, error)
 	GetDatabaseServiceOwnerID(ctx context.Context, id string) (string, error)
+	GetLastAgentCommandByType(ctx context.Context, arg GetLastAgentCommandByTypeParams) (AgentCommand, error)
 	GetOutboundWebhookByID(ctx context.Context, id uuid.UUID) (OutboundWebhook, error)
 	GetOutboundWebhookByIDAndUser(ctx context.Context, arg GetOutboundWebhookByIDAndUserParams) (OutboundWebhook, error)
 	GetProjectByIDForUser(ctx context.Context, arg GetProjectByIDForUserParams) (Project, error)