refactor: reorganize directory structure to match exam submission spec

q4-scalability/architecture.mmd

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+```mermaid
+graph TD
+    Client((Client Requests <br> 15,000 req/s)) --> WAF[Web Application Firewall]
+    WAF --> LB[ghaymah Load Balancer]
+
+    subgraph Auto-Scaling Group
+        direction LR
+        LB -->|Traffic Distribution| API1[myapp-api Container 1 <br> ~350 req/s]
+        LB --> API2[myapp-api Container 2 <br> ~350 req/s]
+        LB --> API3[myapp-api Container 3]
+        LB -.-> APIN[myapp-api Container N <br> Total: 43 Containers]
+    end
+
+    API1 --> BS1[(ghaymah Block Storage <br> /mnt/data)]
+    API2 --> BS2[(ghaymah Block Storage <br> /mnt/data)]
+    API3 --> BS3[(ghaymah Block Storage <br> /mnt/data)]
+    APIN --> BSN[(ghaymah Block Storage <br> /mnt/data)]
+
+    classDef container fill:#e3f2fd,stroke:#1565c0,stroke-width:2px;
+    classDef lb fill:#fff3e0,stroke:#e65100,stroke-width:2px;
+    classDef storage fill:#e8f5e9,stroke:#2e7d32,stroke-width:2px;
+
+    class API1,API2,API3,APIN container;
+    class LB lb;
+    class BS1,BS2,BS3,BSN storage;
+```

q4-scalability/calculations.md

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+# Capacity Planning: Handling 15,000 req/s
+
+To ensure high availability and responsiveness under a load of 15,000 requests per second, we must calculate the required number of container instances.
+
+## Base Assumptions
+- **Target Load:** 15,000 req/s
+- **Max Capacity per Container:** 500 req/s
+- **Safety Margin:** 30%
+
+## Calculation
+1. **Effective Capacity per Container:** 
+   To maintain a 30% margin, we calculate the effective capacity each container should handle before we consider scaling out.
+   `500 req/s * (1 - 0.30) = 350 req/s`
+
+2. **Total Containers Required:**
+   Divide the total expected load by the effective capacity per container.
+   `15,000 req/s / 350 req/s per container ≈ 42.85`
+
+3. **Rounding Up:**
+   We cannot have a fraction of a container, so we always round up to the next whole number.
+   `ceil(42.85) = 43 containers`
+
+## Conclusion
+To safely handle 15,000 req/s while maintaining a 30% safety margin (which helps absorb sudden traffic spikes or the failure of a few containers), the auto-scaling group should be configured to maintain a baseline of **43 containers** during peak load.