fix(opencode): add git and dev tools to service PATH

The opencode-serve unit ran with systemd's minimal default PATH, so
shell commands invoked by the agent (git, make, nix, node, rg, etc.)
were not found. Set systemd.services.opencode-serve.path on both sgx
and amd to a common dev toolset.

systems/x86_64-linux/amd/opencode.nix

@@ -16,6 +16,23 @@ in
     after = [ "network.target" ];
     wantedBy = [ "multi-user.target" ];
 
+    path = with pkgs; [
+      git
+      bash
+      coreutils
+      findutils
+      gnused
+      gnugrep
+      gawk
+      gnumake
+      nix
+      nodejs
+      ripgrep
+      fd
+      curl
+      which
+    ];
+
     environment = {
       HOME = homeDir;
     };

systems/x86_64-linux/sgx/opencode.nix

@@ -16,6 +16,23 @@ in
     after = [ "network.target" ];
     wantedBy = [ "multi-user.target" ];
 
+    path = with pkgs; [
+      git
+      bash
+      coreutils
+      findutils
+      gnused
+      gnugrep
+      gawk
+      gnumake
+      nix
+      nodejs
+      ripgrep
+      fd
+      curl
+      which
+    ];
+
     environment = {
       HOME = homeDir;
     };