chore: project setup and tooling cleanup (#26)

* add project setup

* add tools to eslint

* remove contributing.md

* update claude md

* chore: simplify CI to single Node.js version (22)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* use node 20

* adjust formatting

* fix linting

* format

* fix layout

* fix: align CI node version to .nvmrc (22), remove redundant gotcha

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
Co-authored-by: arkon <arkon.85@hotmail.com>

src/mux-interface.ts

@@ -7,7 +7,14 @@
  */
 
 import type { EventEmitter } from 'node:events';
-import type { ProcessStats, PersistedRespawnConfig, NiceConfig, ClaudeMode, SessionMode, OpenCodeConfig } from './types.js';
+import type {
+  ProcessStats,
+  PersistedRespawnConfig,
+  NiceConfig,
+  ClaudeMode,
+  SessionMode,
+  OpenCodeConfig,
+} from './types.js';
 
 /**
  * Multiplexer session metadata.