🔒 Add API Key authentication to prevent abuse

- Add API_KEY environment variable check
- Protect /api/calculate-birth-chart endpoint
- Protect /api/generate-chart-svg endpoint
- Keep /health endpoint public for monitoring
- Return 403 error for unauthorized requests

This protects the Astrology API from being abused.

🌟 Created by SisiTheFox

app.py

@@ -1,9 +1,10 @@
 """
 🌟 Astrology API - Ultra Simple Version
 Just returns raw Kerykeion calculations
+🔒 Protected with API Key Authentication
 """
 
-from fastapi import FastAPI, HTTPException
+from fastapi import FastAPI, HTTPException, Header, Depends
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import Response
 from pydantic import BaseModel
@@ -12,10 +13,24 @@ from typing import Optional, Any, Dict
 import logging
 import io
 import re
+import os
 
 logging.basicConfig(level=logging.INFO)
 logger = logging.getLogger(__name__)
 
+# 🔐 API Key Configuration
+API_KEY = os.environ.get("API_KEY", "sisi_default_key_change_me")
+
+
+def verify_api_key(x_api_key: Optional[str] = Header(None)):
+    """Verify API key from request header"""
+    if x_api_key != API_KEY:
+        raise HTTPException(
+            status_code=403,
+            detail="🔒 Invalid or missing API key. Please contact SisiTheFox for access."
+        )
+    return x_api_key
+
 app = FastAPI(title="Sisi Astrology API", version="1.0.0")
 
 def to_ascii_safe(name: str) -> str:
@@ -97,7 +112,11 @@ def house_to_dict(house_model: Any) -> Dict:
     }
 
 @app.post("/api/calculate-birth-chart")
-async def calculate_chart(req: BirthRequest):
+async def calculate_chart(req: BirthRequest, api_key: str = Depends(verify_api_key)):
+    """
+    Calculate birth chart
+    🔒 Requires API Key authentication
+    """
     try:
         logger.info(f"📊 Calculating for: {req.name}")
 
@@ -161,8 +180,11 @@ async def calculate_chart(req: BirthRequest):
 
 
 @app.post("/api/generate-chart-svg")
-async def generate_chart_svg(req: BirthRequest):
-    """Generate professional birth chart SVG with aspects (Kerykeion 4.x)"""
+async def generate_chart_svg(req: BirthRequest, api_key: str = Depends(verify_api_key)):
+    """
+    Generate professional birth chart SVG with aspects (Kerykeion 4.x)
+    🔒 Requires API Key authentication
+    """
     try:
         logger.info(f"🎨 Generating SVG chart for: {req.name}")