fix(mobile): target minSdk for the native lib, move memory-card thumbhash to the core, add native CI

native/scripts/build-linux.sh

@@ -1,10 +1,13 @@
 #!/usr/bin/env bash
-# Cross-build the napi addon for Linux server (x86_64 + aarch64) via zigbuild
-# (no Docker) and stage as .node under dist/server/<target>/.
-# In CI you'd build these natively per-arch instead; this is local convenience.
+# Requires cargo-zigbuild and Zig on PATH.
 set -euo pipefail
 cd "$(dirname "$0")/.."
 
+if ! command -v cargo-zigbuild >/dev/null; then
+    echo "cargo-zigbuild is required" >&2
+    exit 1
+fi
+
 CRATE=immich_core_napi
 
 for t in x86_64-unknown-linux-gnu aarch64-unknown-linux-gnu; do