refactor: rename cmd/server to cmd/deklarix

Matches the project structure and binary name defined in the Deklarix
product spec.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

scripts/build.sh

@@ -45,7 +45,7 @@ for ARCH in "${ARCHS[@]}"; do
     GOARCH=$ARCH GOOS=linux go build \
         -ldflags="-X main.Version=${VERSION} -s -w" \
         -o "$OUT" \
-        ./cmd/server/
+        ./cmd/deklarix/
     log "$ARCH fertig: $(du -sh "$OUT" | cut -f1)"
 done