chore: establish Ekklesia platform foundation

tests/fixtures/boundaries/core-imports-module/core/src/index.ts

@@ -0,0 +1,3 @@
+import { calendar } from "../../modules/calendar/src/index.js";
+
+export const invalidCoreFeature = calendar;

tests/fixtures/boundaries/core-imports-module/modules/calendar/src/index.ts

@@ -0,0 +1 @@
+export const calendar = "calendar";