bin/install.sh: add packer installation

bin/install.sh

@@ -179,6 +179,21 @@ install_task() {
   mark_version task "$ver"
 }
 
+# packer — infrastructure as code build tool (single static binary).
+install_packer() {
+  ver=1.15.4
+  have_version packer "$ver" && { fsay "packer $ver already installed."; return 0; }
+  case "$(fetch_arch)" in
+    x86_64) _packer_arch=amd64 ;;
+    aarch64) _packer_arch=arm64 ;;
+    *) fsay "packer: unsupported arch $(uname -m)"; return 1 ;;
+  esac
+  install_zip_bin \
+    "https://releases.hashicorp.com/packer/$ver/packer_${ver}_linux_$_packer_arch.zip" \
+    packer packer
+  mark_version packer "$ver"
+}
+
 # terragrunt — thin wrapper around tofu/terraform (single static binary).
 install_terragrunt() {
   ver=v1.1.0
@@ -226,6 +241,7 @@ try install_terragrunt
 try install_1p
 try install_opencode
 try install_zarf
+try install_packer
 
 if [ -n "$FAILED" ]; then
   fsay ""