chore: add project documentation framework

.project-docs/20-architecture/module-map.md

@@ -0,0 +1,18 @@
+# Module Map
+
+## Source Layout
+
+| Path | Responsibility | Owner Notes |
+|---|---|---|
+
+## Dependency Direction
+
+- {dependency direction rule}
+
+## Risky Or Sensitive Areas
+
+- {module or path that needs extra care}
+
+## Last Updated
+
+{YYYY-MM-DD}