feat: add readonly role with SELECT permissions for all non-system schemas

- Introduced a new SQL migration script to create a 'readonly' role.
- Granted USAGE on all existing schemas and SELECT on all existing tables to the 'readonly' role.
- Configured default privileges to ensure SELECT access on future tables in non-system schemas.

Author: claudfuen

packages/db/prisma/migrations/20250606154623_add_readonly_role/migration.sql

@@ -0,0 +1,57 @@
+-- This script creates a 'readonly' role with SELECT permissions on all tables
+-- in all non-system schemas, and ensures it gets access to future tables.
+
+-- Create the new role
+DROP ROLE IF EXISTS readonly;
+CREATE ROLE readonly;
+
+-- Grant USAGE on all existing schemas to the 'readonly' role
+DO
+$$
+    DECLARE
+        v_schema_name TEXT;
+    BEGIN
+        FOR v_schema_name IN
+            SELECT schema_name
+            FROM information_schema.schemata
+            WHERE schema_name NOT IN ('pg_catalog', 'information_schema')
+            LOOP
+                EXECUTE format('GRANT USAGE ON SCHEMA %I TO readonly', v_schema_name);
+            END LOOP;
+    END
+$$;
+
+-- Grant SELECT on all existing tables in all non-system schemas to the 'readonly' role
+DO
+$$
+    DECLARE
+        schema_name TEXT;
+        table_name  TEXT;
+    BEGIN
+        FOR schema_name, table_name IN
+            SELECT t.table_schema, t.table_name
+            FROM information_schema.tables t
+            WHERE t.table_type = 'BASE TABLE'
+              AND t.table_schema NOT IN ('pg_catalog', 'information_schema')
+            LOOP
+                EXECUTE format('GRANT SELECT ON TABLE %I.%I TO readonly', schema_name, table_name);
+            END LOOP;
+    END
+$$;
+
+-- Grant SELECT on all future tables in all non-system schemas
+DO
+$$
+    DECLARE
+        v_schema_name TEXT;
+    BEGIN
+        FOR v_schema_name IN
+            SELECT schema_name
+            FROM information_schema.schemata
+            WHERE schema_name NOT IN ('pg_catalog', 'information_schema')
+            LOOP
+                EXECUTE format('ALTER DEFAULT PRIVILEGES IN SCHEMA %I GRANT SELECT ON TABLES TO readonly',
+                               v_schema_name);
+            END LOOP;
+    END
+$$;