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)

styles-modern.css

@@ -121,8 +121,8 @@ body {
     font-weight: 400;
 }
 
-/* Indicateur de statut SignalR */
-.signalr-status {
+/* Indicateur de statut serveur */
+.server-status {
     display: flex;
     align-items: center;
     justify-content: center;
@@ -134,7 +134,7 @@ body {
     font-size: 14px;
 }
 
-.signalr-indicator {
+.server-indicator {
     width: 12px;
     height: 12px;
     border-radius: 50%;
@@ -142,27 +142,27 @@ body {
     transition: background 0.3s;
 }
 
-.signalr-indicator.connected {
+.server-indicator.connected {
     background: #4CAF50;
     animation: pulse 2s infinite;
 }
 
-.signalr-indicator.connecting {
+.server-indicator.connecting {
     background: #FFC107;
     animation: pulse 1s infinite;
 }
 
-.signalr-indicator.disconnected,
-.signalr-indicator.error {
+.server-indicator.disconnected,
+.server-indicator.error {
     background: #F44336;
 }
 
-.signalr-indicator.reconnecting {
+.server-indicator.reconnecting {
     background: #FFC107;
     animation: pulse 1.5s infinite;
 }
 
-.signalr-indicator.disabled {
+.server-indicator.disabled {
     background: #9E9E9E;
 }