feat(fpagent): pick the installer bundle for the host architecture

The hosted installer only ever chose the x86_64 bundle, so a 32-bit field
laptop running the public one-liner failed with "no compatible bundle" even
though fingerprint-agent v1.5.0 publishes fpagent-<version>-linux-i386.tar.gz.

Resolve the host architecture from uname -m (x86_64 or i386, else fail before
any download), then prefer -ubuntu-<codename>-<arch>.tar.gz and fall back to
-linux-<arch>.tar.gz. The version regex now derives the git hash for every
supported architecture, so a 32-bit install records and reports it too.

The help text matches the bundle installer: the systemd service and the
self-update timer are on by default, with --no-service, --no-updates and
--update-base documented.

tools/public/fpagent/install.sh

@@ -11,7 +11,7 @@
 # own installer, which handles libfprint, the udev rule, plugdev and the
 # systemd service. Every flag is forwarded to that installer, e.g.:
 #
-#   curl -fsSL https://tools.yrka.app/fpagent/install.sh | bash -s -- --enable-service
+#   curl -fsSL https://tools.yrka.app/fpagent/install.sh | bash -s -- --service-user alice
 #   curl -fsSL https://tools.yrka.app/fpagent/install.sh | bash -s -- --check
 #
 # The private release is reached through the tools app, so no credentials are
@@ -35,12 +35,18 @@ Options:
 Options below are forwarded to the bundled installer:
   --check                 preflight and report only; change nothing
   --offline               never touch the network; fail if dependencies are missing
-  --enable-service        install and enable a systemd service (starts at boot)
+  --no-service            do not install the systemd service (also disables updates)
+  --no-updates            do not install the self-update timer
+  --update-base URL       release base for self-update
+                          (default: https://tools.yrka.app/fpagent)
   --service-user NAME     user for the service (default: the invoking user)
   --install-path PATH     binary destination (default: /usr/local/bin/fpagent)
   --uninstall             remove the binary, the udev rule and the service
   -h, --help              the installer's help
 
+The systemd service and the self-update timer are installed and enabled by
+default; --no-service and --no-updates turn them off.
+
 Environment:
   FPAGENT_BASE_URL        override the download base (default: ${BASE})
 EOF
@@ -85,6 +91,15 @@ find "$tmpbase" -maxdepth 1 -mindepth 1 -type d -uid "$(id -u)" \
 # online bundle (whose installer apt-get's the dependency).
 codename="$(sed -n 's/^VERSION_CODENAME=//p' /etc/os-release 2>/dev/null | tr -d '"')"
 
+# Releases are named for the target architecture; only these two are published.
+# Mirrors the bundled installer's own preflight so both reject the same hosts.
+host_machine="$(uname -m)"
+case "$host_machine" in
+	x86_64 | amd64) arch="x86_64" ;;
+	i386 | i486 | i586 | i686) arch="i386" ;;
+	*) die "unsupported architecture: ${host_machine} (x86_64 or i386 required)" ;;
+esac
+
 if [ "$RELEASE_TAG" = "latest" ]; then
 	meta_url="${BASE}/releases/latest"
 else
@@ -96,25 +111,25 @@ meta="$(curl -fsSL "$meta_url")" || die "could not fetch the release list from $
 
 readout="$(python3 -c '
 import json, re, sys
-codename = sys.argv[1]
-release = json.loads(sys.argv[2])
+codename, arch = sys.argv[1], sys.argv[2]
+release = json.loads(sys.argv[3])
 assets = [a["name"] for a in release.get("assets", [])]
 
 def pick(suffix):
     return next((n for n in assets if n.endswith(suffix) and not n.endswith(".sha256")), "")
 
-name = pick("-ubuntu-" + codename + "-x86_64.tar.gz") if codename else ""
+name = pick("-ubuntu-" + codename + "-" + arch + ".tar.gz") if codename else ""
 if not name:
-    name = pick("-linux-x86_64.tar.gz")
+    name = pick("-linux-" + arch + ".tar.gz")
 # The git hash is baked into the asset name (bundle.sh --version) and into
 # the binary itself; it is the version we record and later compare against.
-m = re.match(r"^fpagent-(.+)-(?:linux-x86_64|ubuntu-[a-z0-9]+-x86_64)\.tar\.gz$", name)
+m = re.match(r"^fpagent-(.+)-(?:linux|ubuntu-[a-z0-9]+)-" + re.escape(arch) + r"\.tar\.gz$", name)
 version = m.group(1) if m else ""
 print(release.get("tag", "") + "\t" + name + "\t" + version)
-' "$codename" "$meta")" || die "could not parse the release metadata"
+' "$codename" "$arch" "$meta")" || die "could not parse the release metadata"
 
 IFS=$'\t' read -r tag asset version <<<"$readout"
-[ -n "$tag" ] && [ -n "$asset" ] || die "no compatible bundle in release ${RELEASE_TAG} (x86_64 required)"
+[ -n "$tag" ] && [ -n "$asset" ] || die "no compatible bundle in release ${RELEASE_TAG} (${arch} required)"
 
 say "  release ${tag}"
 say "  bundle  ${asset}"