feat: implement full client UI from mockup — 10 phases, 331 tests

Client UI:
- Design system: Colors, Typography, Controls resource dictionaries
- Message actions: reply compose bar, hover edit/delete/reply buttons
- Rich content: code blocks, attachments, system messages, content parser
- Server strip: 72px sidebar with server icons, home button, add server
- Status picker: popup for changing online/idle/dnd/invisible status
- ConnectPage: server health check dots with auto-refresh
- User popup: profile card with banner, avatar, roles, member since
- Emoji picker: 6 categories, search, grid of Unicode emojis
- Settings overlay: full-screen with sidebar navigation
- Friends/DM view: sidebar + friends list with tabs (online/all/pending)
- Toast notifications: auto-dismiss after 3s with fade animation

Models & services:
- Attachment model added to Message, ApiMessage, ChatMessagePayload
- EditMessageAsync, DeleteMessageAsync, SendStatusChangeAsync APIs
- MessageContentParser (code blocks, inline code, bold, italic)
- EmojiData, ToastService, HealthStatusToBrushConverter

Server (from prior session):
- Voice room management, SFU, speaker detection
- ACME/TLS support, config improvements
- Protocol and schema updates

Tests: 331 passing (61 converter + 24 voice service + 34 voice VM +
41 parser + 9 edit/delete + existing)

Server/config/config.go

@@ -29,12 +29,18 @@ type GitHubConfig struct {
 	Token string `koanf:"token"`
 }
 
-// VoiceConfig holds STUN/TURN server settings for WebRTC signaling.
+// VoiceConfig holds STUN/TURN server settings and SFU configuration.
 type VoiceConfig struct {
-	TURNSecret  string `koanf:"turn_secret"`  // HMAC-SHA1 secret; auto-generated if empty
-	STUNPort    int    `koanf:"stun_port"`    // default 3478
-	TURNPort    int    `koanf:"turn_port"`    // default 3478
-	TURNEnabled bool   `koanf:"turn_enabled"` // default true
+	TURNSecret      string `koanf:"turn_secret"`      // HMAC-SHA1 secret; auto-generated if empty
+	STUNPort        int    `koanf:"stun_port"`         // default 3478
+	TURNPort        int    `koanf:"turn_port"`         // default 3478
+	TURNEnabled     bool   `koanf:"turn_enabled"`      // default true
+	Quality         string `koanf:"quality"`            // low | medium | high
+	MixingThreshold int    `koanf:"mixing_threshold"`   // selective forwarding threshold
+	TopSpeakers     int    `koanf:"top_speakers"`       // top-N speakers in selective mode
+	ExternalIP      string `koanf:"external_ip"`        // set if behind NAT
+	MediaPortMin    int    `koanf:"media_port_min"`     // UDP port range start for WebRTC media
+	MediaPortMax    int    `koanf:"media_port_max"`     // UDP port range end for WebRTC media
 }
 
 // ServerConfig holds HTTP server settings.
@@ -90,9 +96,14 @@ func defaults() Config {
 			StorageDir: "data/uploads",
 		},
 		Voice: VoiceConfig{
-			STUNPort:    3478,
-			TURNPort:    3478,
-			TURNEnabled: true,
+			STUNPort:        3478,
+			TURNPort:        3478,
+			TURNEnabled:     true,
+			Quality:         "medium",
+			MixingThreshold: 10,
+			TopSpeakers:     3,
+			MediaPortMin:    10000,
+			MediaPortMax:    10100,
 		},
 		GitHub: GitHubConfig{},
 	}

Server/config/config_test.go

@@ -226,6 +226,82 @@ tls:
 	}
 }
 
+func TestLoadVoiceConfigDefaults(t *testing.T) {
+	tmpDir := t.TempDir()
+	cfgPath := filepath.Join(tmpDir, "config.yaml")
+
+	cfg, err := config.Load(cfgPath)
+	if err != nil {
+		t.Fatalf("Load() returned error: %v", err)
+	}
+
+	tests := []struct {
+		name string
+		got  interface{}
+		want interface{}
+	}{
+		{"Voice.Quality", cfg.Voice.Quality, "medium"},
+		{"Voice.MixingThreshold", cfg.Voice.MixingThreshold, 10},
+		{"Voice.TopSpeakers", cfg.Voice.TopSpeakers, 3},
+		{"Voice.ExternalIP", cfg.Voice.ExternalIP, ""},
+		{"Voice.MediaPortMin", cfg.Voice.MediaPortMin, 10000},
+		{"Voice.MediaPortMax", cfg.Voice.MediaPortMax, 10100},
+		{"Voice.STUNPort", cfg.Voice.STUNPort, 3478},
+		{"Voice.TURNPort", cfg.Voice.TURNPort, 3478},
+		{"Voice.TURNEnabled", cfg.Voice.TURNEnabled, true},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			if tc.got != tc.want {
+				t.Errorf("got %v, want %v", tc.got, tc.want)
+			}
+		})
+	}
+}
+
+func TestLoadVoiceConfigFromYAML(t *testing.T) {
+	tmpDir := t.TempDir()
+	cfgPath := filepath.Join(tmpDir, "config.yaml")
+
+	yaml := `
+voice:
+  quality: high
+  mixing_threshold: 5
+  top_speakers: 4
+  external_ip: "1.2.3.4"
+  media_port_min: 20000
+  media_port_max: 20500
+`
+	if err := os.WriteFile(cfgPath, []byte(yaml), 0o644); err != nil {
+		t.Fatalf("failed to write yaml: %v", err)
+	}
+
+	cfg, err := config.Load(cfgPath)
+	if err != nil {
+		t.Fatalf("Load() returned error: %v", err)
+	}
+
+	if cfg.Voice.Quality != "high" {
+		t.Errorf("Voice.Quality = %q, want 'high'", cfg.Voice.Quality)
+	}
+	if cfg.Voice.MixingThreshold != 5 {
+		t.Errorf("Voice.MixingThreshold = %d, want 5", cfg.Voice.MixingThreshold)
+	}
+	if cfg.Voice.TopSpeakers != 4 {
+		t.Errorf("Voice.TopSpeakers = %d, want 4", cfg.Voice.TopSpeakers)
+	}
+	if cfg.Voice.ExternalIP != "1.2.3.4" {
+		t.Errorf("Voice.ExternalIP = %q, want '1.2.3.4'", cfg.Voice.ExternalIP)
+	}
+	if cfg.Voice.MediaPortMin != 20000 {
+		t.Errorf("Voice.MediaPortMin = %d, want 20000", cfg.Voice.MediaPortMin)
+	}
+	if cfg.Voice.MediaPortMax != 20500 {
+		t.Errorf("Voice.MediaPortMax = %d, want 20500", cfg.Voice.MediaPortMax)
+	}
+}
+
 func TestLoadUploadBoundaryValues(t *testing.T) {
 	tmpDir := t.TempDir()
 	cfgPath := filepath.Join(tmpDir, "config.yaml")