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

components/platform/README.md

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+# Platform Layer
+
+Purpose: hardware and system resource abstraction only.
+
+Allowed examples:
+- Wi-Fi/BLE driver wrappers
+- NVS/time/RTOS/system adapters
+- board-specific IO and transport bindings
+
+Rules:
+- Expose stable APIs in `include/`.
+- Keep private headers in `internal/`.
+- Do not depend on `domain`, `control_plane`, or `app_composition`.