refactor(structure): move layered firmware modules from main to components

components/domain/README.md

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+# Domain Layer
+
+Purpose: business capabilities with single responsibility per domain service.
+
+Rules:
+- Expose stable domain APIs in `include/`.
+- Keep implementation details in `internal/` and `src/`.
+- No direct cross-domain internal state access.
+- Cross-domain interactions must use events or Port interfaces.