dev: NixOS 25.11 매뉴얼 로컬 사본 추가

nixpkgs nixos-25.11 브랜치의 nixos/doc/manual/ 디렉토리를 sparse clone으로
가져와 ~/obsidian/dev/nixos-manual/에 복사. _index.md에 구조/갱신 방법 정리.

오프라인 참조 + AI 에이전트 컨텍스트용. sandbox-tokyo 같은 NixOS 노드 운영 시
빠른 참조로 사용.

dev/nixos-manual/configuration/wireless.section.md

@@ -0,0 +1,74 @@
+# Wireless Networks {#sec-wireless}
+
+For a desktop installation using NetworkManager (e.g., GNOME), you just
+have to make sure the user is in the `networkmanager` group and you can
+skip the rest of this section on wireless networks.
+
+NixOS will start wpa_supplicant for you if you enable this setting:
+
+```nix
+{ networking.wireless.enable = true; }
+```
+
+NixOS lets you specify networks for wpa_supplicant declaratively:
+
+```nix
+{
+  networking.wireless.networks = {
+    # SSID with no spaces or special characters
+    echelon = {
+      psk = "abcdefgh";
+    };
+    # SSID with spaces and/or special characters
+    "echelon's AP" = {
+      psk = "ijklmnop";
+    };
+    # Hidden SSID
+    echelon = {
+      hidden = true;
+      psk = "qrstuvwx";
+    };
+    free.wifi = { }; # Public wireless network
+  };
+}
+```
+
+Be aware that keys will be written to the nix store in plaintext! When
+no networks are set, it will default to using a configuration file at
+`/etc/wpa_supplicant.conf`. You should edit this file yourself to define
+wireless networks, WPA keys and so on (see wpa_supplicant.conf(5)).
+
+If you are using WPA2 you can generate pskRaw key using
+`wpa_passphrase`:
+
+```ShellSession
+$ wpa_passphrase ESSID PSK
+network={
+        ssid="echelon"
+        #psk="abcdefgh"
+        psk=dca6d6ed41f4ab5a984c9f55f6f66d4efdc720ebf66959810f4329bb391c5435
+}
+```
+
+```nix
+{
+  networking.wireless.networks = {
+    echelon = {
+      pskRaw = "dca6d6ed41f4ab5a984c9f55f6f66d4efdc720ebf66959810f4329bb391c5435";
+    };
+  };
+}
+```
+
+or you can use it to directly generate the `wpa_supplicant.conf`:
+
+```ShellSession
+# wpa_passphrase ESSID PSK > /etc/wpa_supplicant.conf
+```
+
+After you have edited the `wpa_supplicant.conf`, you need to restart the
+wpa_supplicant service.
+
+```ShellSession
+# systemctl restart wpa_supplicant.service
+```