feat(diagrams): add comprehensive architecture and use case diagrams for client mobile application

firebase/internal-launchpad/assets/diagrams/legacy/client-mobile-application/use-case-flows.mermaid

@@ -0,0 +1,45 @@
+flowchart TD
+    subgraph "Sign-In Flow"
+        A1[User enters credentials] --> B1{SignInBloc};
+        B1 --> C1[Firebase Auth: signInWithEmailAndPassword];
+        C1 -- Success --> D1[Navigate to Home];
+        C1 -- Failure --> E1[Show error message];
+    end
+
+    subgraph "Password Reset Flow"
+        A2[User requests password reset] --> B2{SignInBloc};
+        B2 --> C2[Firebase Auth: sendPasswordResetEmail];
+        C2 -- Email Sent --> D2[User clicks deep link];
+        D2 --> E2[UI with new password fields];
+        E2 --> F2{SignInBloc};
+        F2 --> G2[Firebase Auth: confirmPasswordReset];
+        G2 -- Success --> H2[Show success message];
+        G2 -- Failure --> I2[Show error message];
+    end
+
+    subgraph "Event Listing Flow"
+        A3[User navigates to Events screen] --> B3{EventsBloc};
+        B3 --> C3[GraphQL Query: getEvents];
+        C3 --> D3[Firestore: events collection];
+        D3 -- Returns event data --> C3;
+        C3 -- Returns data --> B3;
+        B3 --> E3[Display list of events];
+    end
+
+    subgraph "Create Event Flow"
+        A4[User submits new event form] --> B4{CreateEventBloc};
+        B4 --> C4[GraphQL Mutation: createEvent];
+        C4 --> D4[Firestore: events collection];
+        D4 -- Success --> C4;
+        C4 -- Returns success --> B4;
+        B4 --> E4[Navigate to event details];
+    end
+
+    subgraph "Profile Viewing Flow"
+        A5[User navigates to Profile screen] --> B5{ProfileBloc};
+        B5 --> C5[GraphQL Query: getProfile];
+        C5 --> D5[Firestore: users collection];
+        D5 -- Returns profile data --> C5;
+        C5 -- Returns data --> B5;
+        B5 --> E5[Display profile information];
+    end