permissions: homepage, sql + crate, add/remove/view for user

crates/database/migrations/20230507220139_permissions.down.sql

@@ -0,0 +1,2 @@
+drop table if exists permissions;
+drop index if exists permissions_unique_user_role;

crates/database/migrations/20230507220139_permissions.up.sql

@@ -0,0 +1,9 @@
+create table if not exists permissions
+(
+    user       TEXT not null references users (id),
+    role       TEXT not null references roles (name),
+    created_at TEXT not null default CURRENT_TIMESTAMP
+);
+
+-- unique user & role
+create unique index if not exists permissions_unique_user_role on permissions (user, role);