refactor: renommer tous les vestiges SignalR → server (closes #16)

- signalr-indicator → server-indicator (CSS, HTML, JS)
- signalrIndicator/signalrText → serverIndicator/serverText (HTML, JS)
- signalr-status → server-status (CSS, HTML)
- Supprimé docs obsolètes (INTEGRATION_SIGNALR, WORKFLOW_AGENT, changelog)
- Supprimé releases notes anciennes (v1.2.16, v1.3.0, v1.5.0)
- Supprimé README.md, styles.css, .claude/commands/dev.md (obsolètes)

renderer.js

@@ -1228,15 +1228,15 @@ function refreshCurrentWebview() {
 
 // === GESTION INDICATEUR STATUT SERVEUR ===
 function updateServerIndicator(status) {
-    const indicator = document.getElementById('signalrIndicator');
-    const text = document.getElementById('signalrText');
+    const indicator = document.getElementById('serverIndicator');
+    const text = document.getElementById('serverText');
     const loginBtn = document.querySelector('#loginForm button[type="submit"]');
     const terminalSelect = document.getElementById('terminal');
 
     if (!indicator || !text) return;
 
     // Reinitialiser les classes
-    indicator.className = 'signalr-indicator';
+    indicator.className = 'server-indicator';
 
     const serverReady = (status === 'connected');