Replace lib/version.ts with APP_VERSION build arg injected via Docker

Remove the static package.json import in lib/version.ts and instead
pass APP_VERSION as a Docker build arg extracted from package.json by
the CI workflow. Both the builder and runner stages receive APP_VERSION
and GIT_COMMIT_SHA as environment variables, making runtime version
info available via process.env without bundling package.json into the
standalone output.

lib/services/update-check.ts

@@ -1,6 +1,7 @@
 import { createLogger } from "@/lib/logger";
 import { getSetting, setSetting } from "@/lib/services/settings";
-import { APP_VERSION } from "@/lib/version";
+
+const APP_VERSION = process.env.APP_VERSION || "0.0.0";
 
 const log = createLogger("update-check");