Add Tailscale, remove WireGuard and old VPS references

- Enable Tailscale on NixOracle and Nixos
- Add SSH matchBlock for Termux (pixel-7a, port 8022)
- Remove extraHosts entries for vps and NixOracle
- Remove WireGuard config, secrets and age key

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

home/ltadeu6.nix

@@ -467,4 +467,16 @@ PY
   };
 
   programs.home-manager.enable = true;
+
+  programs.ssh = {
+    enable = true;
+    enableDefaultConfig = false;
+    matchBlocks = {
+      termux = {
+        hostname = "pixel-7a";
+        user = "u0_a254";
+        port = 8022;
+      };
+    };
+  };
 }