feat: cleanup removal of old ssh plexer and logic

we also have added the necessary logic to auto prune ephemeral nodes because
headscale doesn't seem to automatically remove them. this change made use of a database
which is now stored in the persistent headplane directory.

app/server/web/agent.ts

@@ -10,12 +10,10 @@ import {
 } from 'node:fs/promises';
 import { exit } from 'node:process';
 import { createInterface } from 'node:readline';
-import { Readable, Writable } from 'node:stream';
 import { setTimeout } from 'node:timers/promises';
 import { type } from 'arktype';
 import { HostInfo } from '~/types';
 import log from '~/utils/log';
-import { SSHMultiplexer, createSSHMultiplexer } from '../agent/ssh';
 import type { HeadplaneConfig } from '../config/schema';
 
 interface LogResponse {
@@ -115,7 +113,6 @@ class AgentManager {
 	>;
 
 	private spawnProcess: ChildProcess | null;
-	multiplexer: SSHMultiplexer | null;
 	private agentId: string | null;
 
 	constructor(
@@ -127,7 +124,6 @@ class AgentManager {
 		this.config = config;
 		this.headscaleUrl = headscaleUrl;
 		this.spawnProcess = null;
-		this.multiplexer = null;
 		this.agentId = null;
 		this.startAgent();
 
@@ -214,14 +210,6 @@ class AgentManager {
 			return;
 		}
 
-		const sshInput = this.spawnProcess.stdio[3];
-		const sshOutput = this.spawnProcess.stdio[4];
-
-		if (sshInput && sshOutput) {
-			log.info('agent', 'Using SSH multiplexer manager');
-			this.multiplexer = createSSHMultiplexer(this.spawnProcess);
-		}
-
 		const rlStdout = createInterface({
 			input: this.spawnProcess.stdout,
 			crlfDelay: Number.POSITIVE_INFINITY,