chore: take the version from VERSION.txt only (0.0.3)

VERSION.txt is embedded into the server and the agent, so a plain
go build reports the real version and build.sh no longer injects it.

build.sh

@@ -5,10 +5,9 @@ set -eu
 
 cd "$(dirname "$0")"
 
-VERSION="${VERSION:-$(cat VERSION.txt 2>/dev/null || echo 0.0.0)}"
-PKG="github.com/x-grk/longpolling-remote-access"
-LDFLAGS="-s -w -X $PKG/internal/server.Version=$VERSION -X $PKG/internal/agent.Version=$VERSION"
-echo ">> version $VERSION"
+# The version comes from VERSION.txt, which is embedded into every binary.
+LDFLAGS="-s -w"
+echo ">> version $(cat VERSION.txt)"
 
 mkdir -p dist bin