feat: implement Instagram clone SocialPhoto API

- FastAPI backend with SQLite database
- JWT authentication (register, login)
- User profiles with follow/unfollow
- Posts with image upload and likes/dislikes
- Comments with likes
- Global and personalized feed
- Comprehensive pytest test suite (37 tests)

TASK-ID: 758f4029-702

app/main.py

@@ -0,0 +1,69 @@
+"""SocialPhoto - Instagram Clone API.
+
+A simple social media API for sharing images with likes, comments, and user follows.
+"""
+from pathlib import Path
+
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+from fastapi.staticfiles import StaticFiles
+
+from app.database import init_db
+from app.routes import auth, comments, feed, posts, users
+
+# Create FastAPI app
+app = FastAPI(
+    title="SocialPhoto",
+    description="Instagram Clone API - Share images with likes, comments, and follows",
+    version="1.0.0",
+)
+
+# CORS middleware
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+# Mount uploads directory
+UPLOAD_DIR = Path(__file__).parent.parent / "uploads"
+UPLOAD_DIR.mkdir(parents=True, exist_ok=True)
+app.mount("/uploads", StaticFiles(directory=str(UPLOAD_DIR)), name="uploads")
+
+
+@app.on_event("startup")
+async def startup_event():
+    """Initialize database on startup."""
+    init_db()
+
+
+# Include routers
+app.include_router(auth.router)
+app.include_router(users.router)
+app.include_router(posts.router)
+app.include_router(comments.router)
+app.include_router(feed.router)
+
+
+@app.get("/", tags=["Root"])
+async def root():
+    """Root endpoint."""
+    return {
+        "name": "SocialPhoto",
+        "version": "1.0.0",
+        "description": "Instagram Clone API",
+    }
+
+
+@app.get("/health", tags=["Health"])
+async def health_check():
+    """Health check endpoint."""
+    return {"status": "healthy"}
+
+
+if __name__ == "__main__":
+    import uvicorn
+
+    uvicorn.run(app, host="0.0.0.0", port=8000)