Add Cloudflare email and collaboration workflows

apps/server/internal/database/migrations/000017_watcher_constraints.up.sql

@@ -0,0 +1,14 @@
+DELETE FROM watchers
+WHERE rowid NOT IN (
+    SELECT MIN(rowid)
+    FROM watchers
+    GROUP BY user_id, document_id, folder_path
+);
+
+CREATE UNIQUE INDEX IF NOT EXISTS idx_watchers_user_document_unique
+ON watchers(user_id, document_id)
+WHERE document_id IS NOT NULL;
+
+CREATE UNIQUE INDEX IF NOT EXISTS idx_watchers_user_folder_unique
+ON watchers(user_id, folder_path)
+WHERE folder_path IS NOT NULL;