perf(release): compress single-file binaries (~104MB -> ~53MB)

Enable EnableCompressionInSingleFile so the self-contained release
binaries download roughly half as large. This shrinks the payload the
Netdocs action must write on CI runners, reducing the chance of a
local write failure (curl exit 23) on runners with tight disk/temp.

Also make the action's download failure diagnostics actionable: on a
failed curl fallback or empty-file guard, print the partial file size
and full `df -h` for every mount so disk exhaustion is obvious.

Verified locally: a compressed, isolated win-x64 exe (only netdocs.exe,
no loose theme) builds the full 244-page Web site; the embedded theme
extracts correctly from the compressed bundle.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Netdocs

.github/workflows/packages.yml

@@ -43,6 +43,7 @@ jobs:
             echo "::group::publish $rid"
             dotnet publish src/Netdocs.Cli -c Release -r "$rid" --self-contained \
               -p:PublishSingleFile=true -p:IncludeNativeLibrariesForSelfExtract=true \
+              -p:EnableCompressionInSingleFile=true \
               -p:Version="${VERSION:-0.0.0}" -o "dist/$rid"
             echo "::endgroup::"
           done

action.yml

@@ -111,10 +111,15 @@ runs:
         if [ -z "${download_ok}" ]; then
           tmp="${dest}.partial"
           rm -f "${tmp}"
-          curl --fail --location --show-error --silent \
+          if ! curl --fail --location --show-error --silent \
                --retry 5 --retry-delay 3 --retry-all-errors \
                --connect-timeout 30 \
-               -o "${tmp}" "${url}"
+               -o "${tmp}" "${url}"; then
+            echo "::error::Failed to download ${url}." >&2
+            echo "Partial file size:"; ls -l "${tmp}" 2>/dev/null || true
+            echo "Filesystem usage (all mounts):"; df -h || true
+            exit 1
+          fi
           mv -f "${tmp}" "${dest}"
         fi
 
@@ -123,7 +128,7 @@ runs:
         # Guard against a zero-byte / truncated download slipping through.
         if [ ! -s "${dest}" ]; then
           echo "::error::Downloaded Netdocs binary is missing or empty: ${dest}" >&2
-          df -h "${dest_dir}" || true
+          echo "Filesystem usage (all mounts):"; df -h || true
           exit 1
         fi