first pass of merging in warp (doesn't build)

crates/persistence/migrations/2026-06-01-000000_add_tab_groups/down.sql

@@ -0,0 +1,2 @@
+ALTER TABLE tabs DROP COLUMN tab_group_id;
+DROP TABLE tab_groups;

crates/persistence/migrations/2026-06-01-000000_add_tab_groups/up.sql

@@ -0,0 +1,10 @@
+CREATE TABLE tab_groups (
+  id INTEGER PRIMARY KEY NOT NULL,
+  window_id INTEGER NOT NULL,
+  name TEXT,
+  color TEXT,
+  collapsed BOOLEAN NOT NULL,
+  FOREIGN KEY(window_id) REFERENCES windows(id)
+);
+
+ALTER TABLE tabs ADD COLUMN tab_group_id INTEGER REFERENCES tab_groups(id);