feat: page labels/tags (#2188)

* feat: labels (WIP)
* full implementation

apps/server/src/database/migrations/20260509T121236-labels.ts

@@ -0,0 +1,59 @@
+import { type Kysely, sql } from 'kysely';
+
+export async function up(db: Kysely<any>): Promise<void> {
+  await db.schema
+    .createTable('labels')
+    .addColumn('id', 'uuid', (col) =>
+      col.primaryKey().defaultTo(sql`gen_uuid_v7()`),
+    )
+    .addColumn('name', 'varchar', (col) => col.notNull())
+    .addColumn('type', 'varchar', (col) => col.notNull().defaultTo('page'))
+    .addColumn('workspace_id', 'uuid', (col) =>
+      col.references('workspaces.id').onDelete('cascade').notNull(),
+    )
+    .addColumn('created_at', 'timestamptz', (col) =>
+      col.notNull().defaultTo(sql`now()`),
+    )
+    .addColumn('updated_at', 'timestamptz', (col) =>
+      col.notNull().defaultTo(sql`now()`),
+    )
+    .execute();
+
+  await db.schema
+    .createIndex('labels_workspace_id_type_name_unique')
+    .on('labels')
+    .columns(['workspace_id', 'type', 'name'])
+    .unique()
+    .execute();
+
+  await db.schema
+    .createTable('page_labels')
+    .addColumn('id', 'uuid', (col) =>
+      col.primaryKey().defaultTo(sql`gen_uuid_v7()`),
+    )
+    .addColumn('page_id', 'uuid', (col) =>
+      col.references('pages.id').onDelete('cascade').notNull(),
+    )
+    .addColumn('label_id', 'uuid', (col) =>
+      col.references('labels.id').onDelete('cascade').notNull(),
+    )
+    .addColumn('created_at', 'timestamptz', (col) =>
+      col.notNull().defaultTo(sql`now()`),
+    )
+    .addUniqueConstraint('page_labels_page_id_label_id_unique', [
+      'page_id',
+      'label_id',
+    ])
+    .execute();
+
+  await db.schema
+    .createIndex('page_labels_label_id_idx')
+    .on('page_labels')
+    .column('label_id')
+    .execute();
+}
+
+export async function down(db: Kysely<any>): Promise<void> {
+  await db.schema.dropTable('page_labels').execute();
+  await db.schema.dropTable('labels').execute();
+}