feat(migration): migrate legacy owner data and update config reference handling

- Implemented a migration process to move resources from the legacy owner "default" to the new default owner "local", ensuring no data loss during the transition.
- Updated configuration reference handling to replace legacy `$VAR_`, `$SECRET_`, and `$CONTEXT_` prefixes with mustache-style `{{ vars.name }}`, `{{ secrets.name }}`, and `{{ context.name }}`.
- Enhanced YAML configuration files and scripts to reflect the new mustache syntax, improving consistency across the application.
- Added tests to validate the migration process and ensure proper handling of legacy references.
- Updated documentation to guide users on the new configuration reference format.

packages/server/migrations/20260823150000_owner_default_to_local.js

@@ -0,0 +1,16 @@
+/**
+ * No-op Knex marker: owner + config-ref migrate runs in owner-migrate.js at startup
+ * (needs filesystem + DB together). Kept so deploy tooling sees a versioned step.
+ *
+ * @param {import("knex").Knex} _knex
+ */
+export async function up(_knex) {
+  // Intentionally empty — see migrateDefaultOwnerIfNeeded().
+}
+
+/**
+ * @param {import("knex").Knex} _knex
+ */
+export async function down(_knex) {
+  // Irreversible data migrate.
+}