feat: add connection status indicator (Issue #28)

Adds a colored dot next to the '⚡ Hermes' brand header in the
navigation drawer:
  - Green: connected
  - Yellow: connecting / reconnecting
  - Red: disconnected

Uses a StateFlow on HermesWsClient that tracks the WebSocket
connection lifecycle and is collected in the drawer header.

app/src/main/java/com/m57/hermescontrol/Navigation.kt

@@ -1,5 +1,8 @@
 package com.m57.hermescontrol
 
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.WindowInsets
 import androidx.compose.foundation.layout.fillMaxSize
@@ -7,7 +10,10 @@ import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.navigationBars
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.safeDrawingPadding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.foundation.verticalScroll
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.filled.Chat
@@ -39,12 +45,15 @@ import androidx.compose.material3.NavigationDrawerItemDefaults
 import androidx.compose.material3.Scaffold
 import androidx.compose.material3.Text
 import androidx.compose.material3.rememberDrawerState
+import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.vector.ImageVector
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.unit.dp
@@ -53,6 +62,8 @@ import androidx.navigation3.runtime.entryProvider
 import androidx.navigation3.runtime.rememberNavBackStack
 import androidx.navigation3.ui.NavDisplay
 import com.m57.hermescontrol.data.local.AuthManager
+import com.m57.hermescontrol.data.ws.ConnectionStatus
+import com.m57.hermescontrol.data.ws.HermesWsClient
 import kotlinx.coroutines.launch
 import com.m57.hermescontrol.ui.achievements.AchievementsScreen as AchievementsScreenContent
 import com.m57.hermescontrol.ui.channels.ChannelsScreen as ChannelsScreenContent
@@ -188,16 +199,34 @@ fun MainNavigation() {
                 ModalDrawerSheet(
                     modifier = Modifier.verticalScroll(rememberScrollState()),
                 ) {
-                    // Brand header
-                    Text(
-                        text = "⚡ Hermes",
+                    // Brand header with connection status
+                    val connectionStatus by HermesWsClient.connectionStatus.collectAsState()
+                    val statusColor = when (connectionStatus) {
+                        ConnectionStatus.CONNECTED -> Color(0xFF4CAF50)    // green
+                        ConnectionStatus.CONNECTING,
+                        ConnectionStatus.RECONNECTING -> Color(0xFFFFC107) // yellow
+                        ConnectionStatus.DISCONNECTED -> Color(0xFFF44336) // red
+                    }
+                    Row(
+                        verticalAlignment = Alignment.CenterVertically,
                         modifier = Modifier.padding(start = 20.dp, top = 20.dp, end = 16.dp, bottom = 4.dp),
-                        style =
-                            MaterialTheme.typography.headlineSmall.copy(
-                                fontWeight = FontWeight.Bold,
-                            ),
-                        color = MaterialTheme.colorScheme.primary,
-                    )
+                    ) {
+                        Text(
+                            text = "⚡ Hermes",
+                            style =
+                                MaterialTheme.typography.headlineSmall.copy(
+                                    fontWeight = FontWeight.Bold,
+                                ),
+                            color = MaterialTheme.colorScheme.primary,
+                        )
+                        Spacer(modifier = Modifier.width(8.dp))
+                        Box(
+                            modifier =
+                                Modifier
+                                    .size(10.dp)
+                                    .background(color = statusColor, shape = CircleShape),
+                        )
+                    }
                     Text(
                         text = "AI Agent Control",
                         modifier = Modifier.padding(start = 20.dp, bottom = 12.dp, end = 16.dp),