feat(wechat): native nixpkgs package with app-scoped data (#492)

Switch to the native deb package from nixpkgs-patched (#560225), remove the AppImage/FHS bwrap layer, and enable native Wayland while keeping the X11 fallback.

Keep only WeChat state under one app-scoped HOME and bind the host Documents and Downloads directories like the other desktop apps. User-selected files also go through the XDG FileChooser portal. Remove the launcher, activation script, and compatibility symlinks.

Assisted-by: DeepSeek Harness (deepseek-flash)

outputs/aarch64-linux/src/12kingdoms-shoukei.nix

@@ -23,7 +23,6 @@ let
         "hosts/12kingdoms-${name}"
         # nixos hardening
         "hardening/nixpaks"
-        "hardening/bwraps"
       ])
       ++ [
         {

outputs/x86_64-linux/src/idols-ai.nix

@@ -24,7 +24,6 @@ let
         "hosts/idols-${name}"
         # nixos hardening
         "hardening/nixpaks"
-        "hardening/bwraps"
       ])
       ++ [
         {