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/routes/feed.py

@@ -0,0 +1,124 @@
+"""Feed routes for SocialPhoto."""
+import sqlite3
+from typing import List
+
+from fastapi import APIRouter, Depends, Query
+from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
+
+from app.auth import get_current_user_id
+from app.database import get_db, row_to_dict
+from app.models import FeedResponse, PostResponse
+
+router = APIRouter(prefix="/feed", tags=["Feed"])
+security = HTTPBearer()
+
+
+@router.get("", response_model=FeedResponse)
+async def get_followed_feed(
+    limit: int = Query(default=20, ge=1, le=100),
+    offset: int = Query(default=0, ge=0),
+    credentials: HTTPAuthorizationCredentials = Depends(security),
+    conn: sqlite3.Connection = Depends(get_db),
+) -> FeedResponse:
+    """Get feed of posts from users you follow."""
+    user_id = await get_current_user_id(credentials)
+    cursor = conn.cursor()
+
+    # Get posts from followed users
+    cursor.execute(
+        """
+        SELECT
+            p.id, p.user_id, u.username, p.image_path, p.caption, p.created_at,
+            (SELECT COUNT(*) FROM likes WHERE post_id = p.id) as likes_count,
+            (SELECT COUNT(*) FROM dislikes WHERE post_id = p.id) as dislikes_count,
+            (SELECT COUNT(*) FROM comments WHERE post_id = p.id) as comments_count
+        FROM posts p
+        JOIN users u ON p.user_id = u.id
+        WHERE p.user_id IN (
+            SELECT following_id FROM follows WHERE follower_id = ?
+        )
+        ORDER BY p.created_at DESC
+        LIMIT ? OFFSET ?
+        """,
+        (user_id, limit, offset),
+    )
+
+    posts = []
+    for row in cursor.fetchall():
+        post = row_to_dict(row)
+        posts.append(
+            PostResponse(
+                id=post["id"],
+                user_id=post["user_id"],
+                username=post["username"],
+                image_url=f"/uploads/{post['image_path'].split('/')[-1]}",
+                caption=post["caption"],
+                likes_count=post["likes_count"],
+                dislikes_count=post["dislikes_count"],
+                comments_count=post["comments_count"],
+                created_at=post["created_at"],
+            )
+        )
+
+    # Get total count
+    cursor.execute(
+        """
+        SELECT COUNT(*) as total
+        FROM posts p
+        WHERE p.user_id IN (
+            SELECT following_id FROM follows WHERE follower_id = ?
+        )
+        """,
+        (user_id,),
+    )
+    total = cursor.fetchone()["total"]
+
+    return FeedResponse(posts=posts, total=total, limit=limit, offset=offset)
+
+
+@router.get("/global", response_model=FeedResponse)
+async def get_global_feed(
+    limit: int = Query(default=20, ge=1, le=100),
+    offset: int = Query(default=0, ge=0),
+    conn: sqlite3.Connection = Depends(get_db),
+) -> FeedResponse:
+    """Get global feed of all posts."""
+    cursor = conn.cursor()
+
+    cursor.execute(
+        """
+        SELECT
+            p.id, p.user_id, u.username, p.image_path, p.caption, p.created_at,
+            (SELECT COUNT(*) FROM likes WHERE post_id = p.id) as likes_count,
+            (SELECT COUNT(*) FROM dislikes WHERE post_id = p.id) as dislikes_count,
+            (SELECT COUNT(*) FROM comments WHERE post_id = p.id) as comments_count
+        FROM posts p
+        JOIN users u ON p.user_id = u.id
+        ORDER BY p.created_at DESC
+        LIMIT ? OFFSET ?
+        """,
+        (limit, offset),
+    )
+
+    posts = []
+    for row in cursor.fetchall():
+        post = row_to_dict(row)
+        posts.append(
+            PostResponse(
+                id=post["id"],
+                user_id=post["user_id"],
+                username=post["username"],
+                image_url=f"/uploads/{post['image_path'].split('/')[-1]}",
+                caption=post["caption"],
+                likes_count=post["likes_count"],
+                dislikes_count=post["dislikes_count"],
+                comments_count=post["comments_count"],
+                created_at=post["created_at"],
+            )
+        )
+
+    # Get total count
+    cursor.execute("SELECT COUNT(*) as total FROM posts")
+    total = cursor.fetchone()["total"]
+
+    return FeedResponse(posts=posts, total=total, limit=limit, offset=offset)