Linux packaging: substitute the stage path into nfpm.yaml

nfpm expands env vars in version/arch but not in contents[].src, so
${STAGE}/usr/bin/photocraft never matched and both deb/rpm builds failed.
Verified locally with nfpm v2.47.0 (deb + rpm).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packaging/linux/nfpm.yaml

@@ -1,5 +1,6 @@
 # .deb and .rpm packages (nfpm: https://nfpm.goreleaser.com). Run by package.sh, which stages
-# the file tree in $STAGE and exports VERSION, NFPM_ARCH and STAGE.
+# the file tree, substitutes its path for ${STAGE} (nfpm doesn't expand env vars in `src`) and
+# exports VERSION and NFPM_ARCH.
 #
 #   nfpm package -f packaging/linux/nfpm.yaml -p deb -t dist/release/
 name: photocraft

packaging/linux/package.sh

@@ -81,10 +81,12 @@ fi
 # ---- .deb / .rpm --------------------------------------------------------------------------------
 if has deb || has rpm; then
   command -v nfpm >/dev/null || { echo "error: nfpm not found (https://nfpm.goreleaser.com/install/)" >&2; exit 1; }
-  export STAGE VERSION
+  export VERSION
   export NFPM_ARCH="$DEB_ARCH"
+  # nfpm expands env vars in fields like `version` and `arch`, but not in `contents[].src`.
+  sed "s|\${STAGE}|$STAGE|g" "$HERE/nfpm.yaml" >"$WORK/nfpm.yaml"
   for fmt in deb rpm; do
-    if has "$fmt"; then (cd "$ROOT" && nfpm package -f "$HERE/nfpm.yaml" -p "$fmt" -t "$DIST/$BASENAME.$fmt"); fi
+    if has "$fmt"; then (cd "$ROOT" && nfpm package -f "$WORK/nfpm.yaml" -p "$fmt" -t "$DIST/$BASENAME.$fmt"); fi
   done
 fi