phase-1: scaffold platform foundation structure and architecture governance

docs/architecture/foundation/Import-Boundary-Matrix.md

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+# Import Boundary Matrix
+
+Status: Mandatory
+Date: 2026-07-03
+
+## Allowed Import Matrix
+
+Legend:
+
+- Yes: Allowed
+- No: Forbidden
+- Limited: Allowed only via published contracts
+
+| From \ To | Core | Shared | UI Library | Widgets | Layouts | Pages | Features | Facades | Integrations |
+|---|---|---|---|---|---|---|---|---|---|
+| Core | Yes | Yes | No | No | No | No | No | No | Limited |
+| Shared | Yes | Yes | No | No | No | No | No | No | No |
+| UI Library | Shared only | Yes | Yes | No | No | No | No | No | No |
+| Widgets | Shared/Core contracts | Yes | Yes | Yes | No | No | No | Limited | No |
+| Layouts | Shared/Core contracts | Yes | Yes | Yes | Yes | No | No | Limited | No |
+| Pages | Shared/Core contracts | Yes | Yes | Yes | Yes | Yes | No | Yes | No |
+| Features | Shared/Core contracts | Yes | Yes | Yes | Yes | Yes | No direct feature-to-feature | Yes | Limited |
+| Facades | Shared/Core contracts | Yes | No | No | No | No | Limited | Yes | Yes |
+| Integrations | Shared/Core contracts | Yes | No | No | No | No | No | Limited | Yes |
+
+## Additional Constraints
+
+- Features cannot import other features directly.
+- Shared cannot import any feature, page, layout, widget, or UI layer.
+- UI Library cannot import facades, integrations, router, or HttpClient.
+- Core cannot import features.
+- Circular dependencies are forbidden in all directions.
+
+## Enforcement
+
+- Enforce with lint module boundaries.
+- Enforce with dependency graph checks in CI.
+- Merge blocked on violations.