ch32-rs

End-to-end workflow for adding a new WCH RISC-V chip family (CH32x / CH5xx / CH6xx) to the ch32-rs repo — start from a raw vendor SVD and produce a buildable PAC crate. Use this whenever the user mentions adding/integrating a new WCH chip, regenerating ch32-rs for a new MCU, dealing with `xmllint --schema CMSIS-SVD.xsd` validation failures on a WCH SVD, hitting `svdtools` errors like `MissingRegisterError`, or asking why the generated PACs don't use the `riscv` crate. Walks through SVD cleanup (`fix-svd-order.py`), `devices/*.yaml` authoring, `generate.sh` and `makecrates.py` registration, and the WCH-specific PFIC/Qingke gotchas.