feat(api): Add API testing script and quick test guide

backend/API-TEST-GUIDE.md

@@ -0,0 +1,51 @@
+# Quick API Test Commands
+
+## Test from your local machine
+
+### 1. Health Check
+```
+curl http://10.0.10.30:6800/health
+```
+
+### 2. Ready Check
+```
+curl http://10.0.10.30:6800/ready
+```
+
+### 3. Register User
+```
+curl -X POST http://10.0.10.30:6800/api/auth/register \
+  -H "Content-Type: application/json" \
+  -d '{"email": "test@example.com", "password": "SecurePassword123!", "username": "testuser"}'
+```
+
+### 4. Login
+```
+curl -X POST http://10.0.10.30:6800/api/auth/login \
+  -H "Content-Type: application/json" \
+  -d '{"email": "test@example.com", "password": "SecurePassword123!"}'
+```
+
+### 5. Get User Profile (with token)
+```
+TOKEN=$(curl -s -X POST http://10.0.10.30:6800/api/auth/login \
+  -H "Content-Type: application/json" \
+  -d '{"email": "test@example.com", "password": "SecurePassword123!"}' \
+  | jq -r '.access_token')
+
+curl http://10.0.10.30:6800/api/users/me \
+  -H "Authorization: Bearer $TOKEN"
+```
+
+## Test from the server
+```
+cd backend
+./scripts/test-api.sh
+```
+
+## Expected Results
+
+- Health Check: `+`{"status":"ok"}`+`
+- Ready Check: `+`{"status":"ready"}`+`
+- Register: `+`{"message": "User registered successfully", "user_id": "..."}`+`
+- Login: `+`{"access_token": "...", "refresh_token": "...", "token_type": "bearer"}`+`