feat: add public instructor profiles

server/migrations/013_instructor_profiles.sql

@@ -0,0 +1,13 @@
+alter table users
+  add column if not exists avatar_image_url text,
+  add column if not exists profile_headline text not null default '',
+  add column if not exists profile_bio text not null default '',
+  add column if not exists website_url text,
+  add column if not exists linkedin_url text,
+  add column if not exists instagram_url text,
+  add column if not exists youtube_url text,
+  add column if not exists profile_is_public boolean not null default true;
+
+create index if not exists users_public_instructor_profiles_index
+  on users (id)
+  where profile_is_public and role in ('instructor', 'admin');