Upgrade Snell default version to v5.0.1

Update snell_version from v4.1.1 to v5.0.1. Switch download URL from GitHub
Releases to official NSSurge CDN (dl.nssurge.com) as v5 releases are now
hosted there.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -105,7 +105,7 @@ ansible-playbook site.yml --limit trojan
 
 | 变量 | 默认值 | 说明 |
 |------|--------|------|
-| `snell_version` | `v4.1.1` | Snell 版本 |
+| `snell_version` | `v5.0.1` | Snell 版本 |
 | `snell_port` | `61080` | 监听端口 |
 | `snell_psk` | 自动生成 | 预共享密钥 |
 | `snell_ipv6` | `false` | 是否启用 IPv6 |

roles/snell/defaults/main.yml

@@ -1,6 +1,6 @@
 ---
-snell_version: "v4.1.1"
-snell_download_url: "https://github.com/surge-networks/snell/releases/download/{{ snell_version }}/snell-server-{{ snell_version }}-linux-amd64.zip"
+snell_version: "v5.0.1"
+snell_download_url: "https://dl.nssurge.com/snell/snell-server-{{ snell_version }}-linux-amd64.zip"
 snell_port: 61080
 snell_psk: "{{ lookup('password', 'credentials/snell_psk length=32 chars=ascii_letters,digits') }}"
 snell_ipv6: false