feat: rebuild iOS app from API audit + new podcast/media service

iOS App (complete rebuild):
- Audited all fitness API endpoints against live responses
- Models match exact API field names (snapshot_ prefixes, UUID strings)
- FoodEntry uses computed properties (foodName, calories, etc.) wrapping snapshot fields
- Flexible Int/Double decoding for all numeric fields
- AI assistant with raw JSON state management (JSONSerialization, not Codable)
- Home dashboard with custom background, frosted glass calorie widget
- Fitness: Today/Templates/Goals/Foods tabs
- Food search with recent + all sections
- Meal sections with colored accent bars, swipe to delete
- 120fps ProMotion, iOS 17+ @Observable

Podcast/Media Service:
- FastAPI backend for podcast RSS + local audiobook folders
- Shows, episodes, playback progress, queue management
- RSS feed fetching with feedparser + ETag support
- Local folder scanning with mutagen for audio metadata
- HTTP Range streaming for local audio files
- Playback events logging (play/pause/seek/complete)
- Reuses brain's PostgreSQL + Redis
- media_ prefixed tables

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ios/Platform/Platform/ContentView.swift

@@ -1,37 +1,90 @@
 import SwiftUI
 
 struct ContentView: View {
-    @Environment(AuthManager.self) private var authManager
+    @Environment(AuthManager.self) private var auth
 
     var body: some View {
         Group {
-            if authManager.isCheckingAuth {
-                LoadingView(message: "Checking session...")
-            } else if authManager.isLoggedIn {
+            if auth.isCheckingAuth {
+                ProgressView()
+                    .frame(maxWidth: .infinity, maxHeight: .infinity)
+                    .background(Color.canvas)
+            } else if auth.isLoggedIn {
                 MainTabView()
             } else {
                 LoginView()
             }
         }
         .task {
-            await authManager.checkAuth()
+            await auth.checkAuth()
         }
     }
 }
 
 struct MainTabView: View {
-    var body: some View {
-        TabView {
-            HomeView()
-                .tabItem {
-                    Label("Home", systemImage: "house.fill")
-                }
+    @State private var selectedTab = 0
+    @State private var showAssistant = false
 
-            FitnessTabView()
-                .tabItem {
-                    Label("Fitness", systemImage: "flame.fill")
-                }
+    var body: some View {
+        ZStack(alignment: .bottomTrailing) {
+            TabView(selection: $selectedTab) {
+                HomeView()
+                    .tabItem {
+                        Label("Home", systemImage: "house.fill")
+                    }
+                    .tag(0)
+
+                FitnessTabView()
+                    .tabItem {
+                        Label("Fitness", systemImage: "flame.fill")
+                    }
+                    .tag(1)
+            }
+            .tint(Color.accentWarm)
+
+            Button {
+                showAssistant = true
+            } label: {
+                Image(systemName: "plus")
+                    .font(.title2.weight(.semibold))
+                    .foregroundStyle(.white)
+                    .frame(width: 56, height: 56)
+                    .background(Color.accentWarm)
+                    .clipShape(Circle())
+                    .shadow(color: .black.opacity(0.2), radius: 8, y: 4)
+            }
+            .padding(.trailing, 20)
+            .padding(.bottom, 70)
+        }
+        .sheet(isPresented: $showAssistant) {
+            AssistantSheetView()
         }
-        .tint(Color.accentWarm)
+    }
+}
+
+struct AssistantSheetView: View {
+    @State private var selectedMode = 0
+
+    var body: some View {
+        NavigationStack {
+            VStack(spacing: 0) {
+                Picker("Mode", selection: $selectedMode) {
+                    Text("AI Chat").tag(0)
+                    Text("Quick Add").tag(1)
+                }
+                .pickerStyle(.segmented)
+                .padding(.horizontal)
+                .padding(.top, 8)
+
+                if selectedMode == 0 {
+                    AssistantChatView()
+                } else {
+                    FoodSearchView(isSheet: true)
+                }
+            }
+            .navigationTitle("Add Food")
+            .navigationBarTitleDisplayMode(.inline)
+        }
+        .presentationDetents([.large])
     }
 }