feat: define clean architecture layers and ports

docs/architecture/layers.md

@@ -0,0 +1,34 @@
+# Clean Architecture layer contract
+
+The import direction is `domain <- application <- presentation`; concrete
+adapters implement application-owned ports and are assembled only in
+`src/bootstrap`.
+
+| Layer | Owns | May depend on |
+| --- | --- | --- |
+| `domain` | framework-neutral models and pure policies | domain siblings |
+| `application` | use cases, ports, orchestration, view-models | domain and application siblings |
+| `presentation` | routes, components, user interaction and view state | application public API and shared UI |
+| `adapters` | browser and third-party implementations of application ports | application ports and limited domain values |
+| `bootstrap` | runtime configuration, adapter construction and React mount | all selected runtime modules |
+
+The following edges are forbidden:
+
+- domain to application, presentation, adapters, bootstrap, React, or browser globals
+- application to presentation, concrete adapters, bootstrap, React, or browser globals
+- presentation to concrete adapters, raw DTO schemas, or storage implementations
+- an adapter to presentation, bootstrap internals, or another concrete adapter
+
+`bootstrap` contains composition only. Business rules and page-specific
+orchestration belong to domain/application.
+
+Architecture reports use this shape:
+
+```json
+{
+  "schemaVersion": 1,
+  "generatedAt": "ISO-8601",
+  "rules": [{ "name": "rule-id", "severity": "error", "violations": 0 }],
+  "summary": { "errors": 0, "warnings": 0 }
+}
+```