Default static Qt build to host architecture

ober

c8ce4351d1068ad06d416a1b4f3e0a48a5680767

diff --git a/Makefile b/Makefile
index 8791562..12426e1 100644
--- a/Makefile
+++ b/Makefile
@@ -42,11 +42,13 @@ CARGO ?= cargo
 CARGO_AUDIT ?= $(shell command -v cargo-audit 2>/dev/null || printf '%s/.cargo/bin/cargo-audit' "$$HOME")
 CARGO_AUDIT_VERSION ?= 0.22.2
 PODMAN ?= podman
-PODMAN_PLATFORM ?= linux/arm64
+STATIC_QT_HOST_ARCH := $(shell uname -m)
+STATIC_QT_ARCH := $(if $(filter x86_64 amd64,$(STATIC_QT_HOST_ARCH)),amd64,$(if $(filter aarch64 arm64,$(STATIC_QT_HOST_ARCH)),arm64,$(STATIC_QT_HOST_ARCH)))
+PODMAN_PLATFORM ?= linux/$(STATIC_QT_ARCH)
 PODMAN_BUILD_FLAGS ?=
 STATIC_QT_BASE_IMAGE ?= docker.io/library/ubuntu:24.04@sha256:4fbb8e6a8395de5a7550b33509421a2bafbc0aab6c06ba2cef9ebffbc7092d90
 STATIC_QT_IMAGE ?= jerboa-browser-qt-builder
-STATIC_QT_TARBALL ?= jerboa-browser-static-qt-linux-arm64.tar.gz
+STATIC_QT_TARBALL ?= jerboa-browser-static-qt-linux-$(STATIC_QT_ARCH).tar.gz
 STATIC_QT_APT_SNAPSHOT ?= 20260701T000000Z
 
 # Modules that use (std crypto native-rust) need libjerboa_native dlopen-able at
@@ -158,8 +160,17 @@ ensure-jerboa-tools:
 check-podman:
 	@command -v $(PODMAN) >/dev/null 2>&1 || \
 	  { echo "ERROR: Podman executable '$(PODMAN)' not found. Install Podman or set PODMAN=/path/to/podman."; exit 1; }
-	@$(PODMAN) info >/dev/null 2>&1 || \
-	  { echo "ERROR: Podman executable '$(PODMAN)' is installed but not reachable. On macOS/Windows, run 'podman machine start' and retry."; exit 1; }
+	@if ! $(PODMAN) info >/dev/null 2>&1; then \
+	  echo "ERROR: Podman executable '$(PODMAN)' is installed but not usable:" >&2; \
+	  $(PODMAN) info >&2 || true; \
+	  case "$$(uname -s)" in \
+	    Darwin|MINGW*|MSYS*|CYGWIN*) \
+	      echo "On macOS/Windows, initialize and start the VM with: podman machine init && podman machine start" >&2 ;; \
+	    *) \
+	      echo "On Linux, fix the rootless Podman setup above; do not use podman machine." >&2 ;; \
+	  esac; \
+	  exit 1; \
+	fi
 
 # Build the self-contained native ./jerboa-browser via .jerbuild.
 native-static: check-jerbuild