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

crates/persistence/migrations/2026-06-13-000000_drop_welcome_panes/up.sql

@@ -0,0 +1,13 @@
+-- Drop the welcome_panes table first to remove the FK constraint that
+-- references pane_leaves, so we can then clean up the pane_leaves rows.
+DROP TABLE IF EXISTS welcome_panes;
+
+-- Delete pane_leaves rows for welcome panes. These would otherwise cause
+-- "Unrecognized pane kind: welcome" errors in read_node during restoration.
+DELETE FROM pane_leaves WHERE kind = 'welcome';
+
+-- Delete the now-orphaned leaf pane_nodes (those with no corresponding
+-- pane_leaves row).
+DELETE FROM pane_nodes
+    WHERE is_leaf = 1
+    AND id NOT IN (SELECT pane_node_id FROM pane_leaves);