Add voice, image, sessions, search, and header tab switcher

Chowder/Chowder/Info.plist

@@ -7,5 +7,13 @@
 		<key>NSAllowsArbitraryLoads</key>
 		<true/>
 	</dict>
+	<key>NSMicrophoneUsageDescription</key>
+	<string>Chowder uses the microphone for voice input so you can speak your messages.</string>
+	<key>NSSpeechRecognitionUsageDescription</key>
+	<string>Chowder uses speech recognition to transcribe your voice into text messages.</string>
+	<key>NSCameraUsageDescription</key>
+	<string>Chowder uses the camera to take photos for the agent to analyze.</string>
+	<key>NSPhotoLibraryUsageDescription</key>
+	<string>Chowder accesses your photo library to send images to the agent.</string>
 </dict>
 </plist>

Chowder/Chowder/Models/Message.swift

@@ -10,11 +10,13 @@ struct Message: Identifiable, Codable {
     let role: MessageRole
     var content: String
     let timestamp: Date
+    var imageData: Data?
 
-    init(id: UUID = UUID(), role: MessageRole, content: String, timestamp: Date = Date()) {
+    init(id: UUID = UUID(), role: MessageRole, content: String, timestamp: Date = Date(), imageData: Data? = nil) {
         self.id = id
         self.role = role
         self.content = content
         self.timestamp = timestamp
+        self.imageData = imageData
     }
 }

Chowder/Chowder/Models/SavedSession.swift

@@ -0,0 +1,22 @@
+import Foundation
+
+struct SavedSession: Identifiable, Codable, Equatable {
+    let id: UUID
+    var key: String          // e.g. "agent:main:main"
+    var label: String        // user-friendly label e.g. "Main", "Research"
+    var lastUsed: Date
+    var messageCount: Int
+
+    init(id: UUID = UUID(), key: String, label: String, lastUsed: Date = Date(), messageCount: Int = 0) {
+        self.id = id
+        self.key = key
+        self.label = label
+        self.lastUsed = lastUsed
+        self.messageCount = messageCount
+    }
+
+    /// Default session matching the app's initial config.
+    static var defaultSession: SavedSession {
+        SavedSession(key: "agent:main:main", label: "Main")
+    }
+}