Fix icon sizing and category filter

backend/main.py

@@ -67,7 +67,7 @@ def init_db():
             cur.execute("""
             create table if not exists links(
                 id bigint auto_increment primary key,
-                name varchar(255) not null,
+                name varchar(255) not null unique,
                 url text not null,
                 description text,
                 category varchar(255),
@@ -113,6 +113,15 @@ def require_admin(request: Request):
         raise HTTPException(401, "Unauthorized")
     return user
 
+
+def link_name_exists(conn, name: str, *, exclude_id: int | None = None) -> bool:
+    with conn.cursor() as cur:
+        if exclude_id is None:
+            cur.execute("select 1 from links where name=%s limit 1", (name,))
+        else:
+            cur.execute("select 1 from links where name=%s and id<>%s limit 1", (name, exclude_id))
+        return cur.fetchone() is not None
+
 @app.get("/api/me")
 def me(request: Request):
     with db() as c:
@@ -197,6 +206,9 @@ def create_link(
     icon: UploadFile | None = File(None),
 ):
     require_admin(request)
+    with db() as c:
+        if link_name_exists(c, name):
+            raise HTTPException(409, "Link name already exists")
     icon_blob = icon_mime = None
     if icon:
         icon_blob = icon.file.read()
@@ -246,6 +258,8 @@ def update_link(
         icon_mime = icon.content_type
     now = datetime.utcnow().isoformat()
     with db() as c:
+        if link_name_exists(c, name, exclude_id=link_id):
+            raise HTTPException(409, "Link name already exists")
         with c.cursor() as cur:
             if icon_blob:
                 cur.execute("""update links set name=%s,url=%s,description=%s,category=%s,icon_blob=%s,icon_mime=%s,icon_url=%s,enabled=%s,updated_at=%s where id=%s""",