Create AddFeed dto, add validation and sqlx

sql/create.sql

@@ -2,13 +2,13 @@ create table if not exists users(
 	id uuid not null primary key,
 	name text not null,
 	password varchar(100) not null,
-	email text not null
+	email text not null unique
 );
 
 create table if not exists feeds(
 	id uuid not null primary key,
 	name text not null,
-	link text not null,
+	link text not null unique,
 	favicon_url text not null,
 	tags text[] not null,
 	submitter_id uuid not null references users(id)
@@ -16,7 +16,7 @@ create table if not exists feeds(
 
 create table if not exists entries(
 	id uuid not null primary key,
-	feed_id uuid not null references feed(id),
+	feed_id uuid not null references feeds(id),
 	title text not null,
 	link text not null,
 	date timestamp with time zone not null,
@@ -31,6 +31,6 @@ create table if not exists entries_users(
 	is_bookmarked bool not null,
 	is_read_later bool not null,
 	is_ignored bool not null,
-	constraint entries_users_pk primary keys(user_id, feed_id)
+	constraint entries_users_pk primary key(user_id, feed_id)
 );