Fix all high and medium severity security issues found by Bandit

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

app/api/user.py

@@ -23,7 +23,8 @@ async def whoami_handler(request: Request):
         raise HTTPException(status_code=400, detail="User has no email in session")
 
     # Generate Gravatar URL from email
-    email_hash = md5(email.strip().lower().encode()).hexdigest()
+    # MD5 is used here for Gravatar's URL generation (not for security), so usedforsecurity=False
+    email_hash = md5(email.strip().lower().encode(), usedforsecurity=False).hexdigest()
     gravatar_url = f"https://www.gravatar.com/avatar/{email_hash}?d=identicon"
     
     # Add the gravatar URL to the user object instead of creating a new response