Simplify CDC driver layer

docs/host_dri_rebuild.md

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+# Host DRI Rebuild
+
+## Goal
+
+Keep the device runtime layer small and transport-only.
+
+The DRI layer should:
+
+- enumerate endpoints
+- open and close connections
+- read raw bytes
+- write raw bytes
+
+The DRI layer should not:
+
+- parse frames
+- manage protocol state
+- decide handshake success
+
+## Completed Nodes
+
+### Node 1: GATT placeholder
+
+Files:
+
+- `KeyBorad/KeyBorad/DRI/GATT/Dri_Gatt.h`
+- `KeyBorad/KeyBorad/DRI/GATT/Dri_Gatt.cpp`
+
+Design notes:
+
+- reserves the BLE transport position early
+- keeps the implementation small for now
+- avoids mixing GATT transport with logic concerns
+
+### Node 2: CDC transport cleanup
+
+Files updated in this step:
+
+- `KeyBorad/KeyBorad/DRI/Dri_Cdc.h`
+- `KeyBorad/KeyBorad/DRI/Dri_Cdc.cpp`
+
+Design notes:
+
+- remove frame parsing from the driver
+- remove handshake ownership from the driver
+- keep only enumerate/open/close/read-bytes/write-bytes
+
+Implemented behavior:
+
+- list ports with `Dri_Cdc_Enum()`
+- open one port with `Dri_Cdc_Open()`
+- close one port with `Dri_Cdc_Close()`
+- read raw bytes with timeout
+- write raw bytes with timeout
+
+## Next DRI nodes
+
+- implement real GATT discovery and notify/write path
+- provide one simple connection summary for logic layer