Add Gowin FPGA toolchain for desktop development.

Vendor Gowin EDU IDE, add openFPGALoader/Yosys/nextpnr/Apicula, and USB udev rules for Tang boards.

modules/fpga.nix

@@ -0,0 +1,53 @@
+# 高云（Gowin）FPGA 开发：开源工具链 + 教育版 IDE + 下载器权限
+# IDE 包装源自 ryan4yin/nur-packages（本地 vendoring，因上游已注释掉该包）
+{ pkgs, ... }:
+
+let
+  gowin-eda-edu-ide = pkgs.callPackage ../pkgs/gowin-eda-edu-ide { };
+in
+{
+  # openFPGALoader / 串口下载器
+  users.groups.plugdev = { };
+  users.users.whc.extraGroups = [
+    "dialout"
+    "plugdev"
+  ];
+
+  # FTDI / Sipeed Tang 等常见下载器（含 TAG+=uaccess，登录用户可直接访问）
+  services.udev.extraRules = ''
+    # openFPGALoader — FTDI 常见 VID/PID（Tang Nano / Primer 等）
+    ACTION!="add|change", GOTO="gowin_fpga_end"
+    SUBSYSTEM!="usb|tty|hidraw", GOTO="gowin_fpga_end"
+    ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6010", MODE="0664", GROUP="plugdev", TAG+="uaccess"
+    ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6014", MODE="0664", GROUP="plugdev", TAG+="uaccess"
+    ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6015", MODE="0664", GROUP="plugdev", TAG+="uaccess"
+    ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", MODE="0664", GROUP="plugdev", TAG+="uaccess"
+    # Sipeed / CMSIS-DAP 类
+    ATTRS{idVendor}=="1d50", MODE="0664", GROUP="plugdev", TAG+="uaccess"
+    ATTRS{idVendor}=="0d28", ATTRS{idProduct}=="0204", MODE="0664", GROUP="plugdev", TAG+="uaccess"
+    LABEL="gowin_fpga_end"
+  '';
+
+  environment.systemPackages = with pkgs; [
+    # 烧录（官方 Programmer 在 NixOS 上不稳定，优先用这个）
+    openfpgaloader
+
+    # 开源综合 / 布局布线（Apicula → nextpnr himbaechel/gowin）
+    yosys
+    nextpnr
+    python3Packages.apycula
+
+    # 仿真与波形
+    iverilog
+    verilator
+    gtkwave
+
+    # 高云教育版 IDE：gowin-env / gowin-ide → 启动 gw_ide
+    # 强制 X11，避免 Wayland 下 Qt 插件崩溃
+    (writeShellScriptBin "gowin-ide" ''
+      export QT_QPA_PLATFORM=xcb
+      exec ${gowin-eda-edu-ide}/bin/gowin-env "$@"
+    '')
+    gowin-eda-edu-ide
+  ];
+}