gogs: avoid creating symlinks each run

nixos/modules/services/misc/gogs.nix

···
     HTTP_ADDR = ${cfg.httpAddress}
     HTTP_PORT = ${toString cfg.httpPort}
     ROOT_URL = ${cfg.rootUrl}
+    STATIC_ROOT_PATH = ${cfg.staticRootPath}
 
     [session]
     COOKIE_NAME = session
···
         '';
       };
 
+      staticRootPath = mkOption {
+        type = types.str;
+        default = "${pkgs.gogs.data}";
+        example = "/var/lib/gogs/data";
+        description = "Upper level of template and static files path.";
+      };
+
       extraConfig = mkOption {
         type = types.str;
         default = "";
···
         runConfig = "${cfg.stateDir}/custom/conf/app.ini";
         secretKey = "${cfg.stateDir}/custom/conf/secret_key";
       in ''
+        mkdir -p ${cfg.stateDir}
+
         # copy custom configuration and generate a random secret key if needed
         ${optionalString (cfg.useWizard == false) ''
           mkdir -p ${cfg.stateDir}/custom/conf

pkgs/applications/version-management/gogs/default.nix

···
     cp -R $src/{public,templates} $data
 
     wrapProgram $bin/bin/gogs \
-      --prefix PATH : ${makeBinPath [ bash git gzip openssh ]} \
-      --run 'export GOGS_WORK_DIR=''${GOGS_WORK_DIR:-$PWD}' \
-      --run 'mkdir -p "$GOGS_WORK_DIR" && cd "$GOGS_WORK_DIR"' \
-      --run "ln -fs $data/{public,templates} ."
+      --prefix PATH : ${makeBinPath [ bash git gzip openssh ]}
   '';
 
   goPackagePath = "github.com/gogits/gogs";