Add SSH configuration management via nix

- Create modules/ssh.nix with all host configurations
- Import SSH module in flake.nix homeConfiguration
- Manage SSH config declaratively through home-manager

🤖 Generated with [Claude Code](https://claude.ai/code)

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

flake.nix

@@ -43,6 +43,7 @@
         ./modules/nvim.nix 
         ./modules/tmux.nix 
         ./modules/zsh.nix 
+        ./modules/ssh.nix
       ];
 
       home.username = "yanlin";

modules/ssh.nix

@@ -0,0 +1,60 @@
+{ config, pkgs, ... }:
+
+{
+  programs.ssh = {
+    enable = true;
+    
+    matchBlocks = {
+      "aicloud" = {
+        hostname = "aicloud";
+        user = "hb05nk@cs.aau.dk";
+        identityFile = "~/.ssh/keys/aicloud";
+        proxyJump = "pi";
+      };
+
+      "nas" = {
+        hostname = "nas.hw.yanlincs.com";
+        user = "root";
+        identityFile = "~/.ssh/keys/nas";
+      };
+
+      "pi" = {
+        hostname = "pi.hw.yanlincs.com";
+        user = "yanlin";
+        identityFile = "~/.ssh/keys/pi";
+      };
+
+      "cm" = {
+        hostname = "cm.hw.yanlincs.com";
+        user = "yanlin";
+        identityFile = "~/.ssh/keys/pi";
+      };
+
+      "personal-vps" = {
+        hostname = "personal.vps.yanlincs.com";
+        user = "root";
+        identityFile = "~/.ssh/keys/hetzner";
+      };
+
+      "zero" = {
+        hostname = "zero.hw.yanlincs.com";
+        user = "yanlin";
+        identityFile = "~/.ssh/keys/pi";
+      };
+
+      "ucloud-a40" = {
+        hostname = "130.225.38.194";
+        user = "ucloud";
+        identityFile = "~/.ssh/keys/ucloud";
+        proxyJump = "imac";
+      };
+
+      "ucloud-h100" = {
+        hostname = "ssh.cloud.sdu.dk";
+        user = "ucloud";
+        port = 2281;
+        identityFile = "~/.ssh/keys/ucloud";
+      };
+    };
+  };
+}