chore: add migration to fix schema creation and update existing SQL files

This commit introduces a new migration that ensures all necessary schemas and extensions
exist, fixing potential issues with initial setup.
It also updates previous migration
files to remove redundant schema and extension creation, and refactors function and table
definitions for consistency and compatibility with Supabase's reset behavior.
Additionally,
indexes are added to optimize query performance across various tables.

Author: jumski

examples/playground/supabase/migrations/20250429064909_fix_pgflow_schema_creation.sql

@@ -0,0 +1,31 @@
+-- This migration fixes any issues that might occur with the pgflow initial migration
+-- It ensures all required schemas and extensions exist
+
+-- Ensure pgflow schema exists
+do $$
+BEGIN
+  IF NOT EXISTS (SELECT 1 FROM pg_namespace WHERE nspname = 'pgflow') THEN
+    CREATE SCHEMA "pgflow";
+  END IF;
+END
+$$;
+
+-- Ensure pgmq schema exists
+do $$
+BEGIN
+  IF NOT EXISTS (SELECT 1 FROM pg_namespace WHERE nspname = 'pgmq') THEN
+    CREATE SCHEMA "pgmq";
+  END IF;
+END
+$$;
+
+-- Ensure pgmq extension exists
+do $$
+BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM pg_extension WHERE extname = 'pgmq'
+  ) THEN
+    CREATE EXTENSION "pgmq" WITH SCHEMA "pgmq" VERSION "1.4.4";
+  END IF;
+END
+$$;