Fix ox-hugo export with internal ID links and Quartz config

- Add org-id resolution for [[id:...]] links by building ID locations
  database once before parallel export
- Handle broken file links gracefully with org-export-with-broken-links
- Fix race condition in parallel exports by pre-building ID cache
- Fix Quartz config not being applied: cp was preserving nix store hash
  prefix in filename instead of using explicit destination filename
- Continue pipeline even when some exports fail, reporting failures
- Improve error handling and logging throughout export pipeline

lib/org_garden/cli.ex

@@ -136,10 +136,13 @@ defmodule OrgGarden.CLI do
 
     # Full batch export
     wipe(content_dir)
-    export_all(notes_dir, output_dir)
+    export_result = export_all(notes_dir, output_dir)
     run_pipeline(content_dir, pipeline_opts)
     generate_index(content_dir)
 
+    # Track if we had export failures
+    had_export_failures = match?({:error, _}, export_result)
+
     node_path = Config.get(:node_path, "node")
 
     IO.puts("==> Building static site with Quartz...")
@@ -166,6 +169,11 @@ defmodule OrgGarden.CLI do
     end
 
     IO.puts("==> Build complete. Output: #{Path.join(output_dir, "public")}")
+
+    # Exit with error if there were export failures
+    if had_export_failures do
+      System.halt(1)
+    end
   end
 
   defp parse_build_args(argv) do
@@ -191,7 +199,7 @@ defmodule OrgGarden.CLI do
 
     # Phase 1-4: full batch export
     wipe(content_dir)
-    export_all(notes_dir, output_dir)
+    export_result = export_all(notes_dir, output_dir)
     run_pipeline(content_dir, pipeline_opts)
     generate_index(content_dir)
 
@@ -203,6 +211,12 @@ defmodule OrgGarden.CLI do
 
     IO.puts("==> Done. #{md_count} markdown files in #{content_dir}")
 
+    # Exit with error if there were export failures (unless in watch mode)
+    case {export_result, watch?} do
+      {{:error, _}, false} -> System.halt(1)
+      _ -> :ok
+    end
+
     # Phase 5: optional watch mode
     if watch? do
       IO.puts("==> Watching #{notes_dir} for .org changes... (Ctrl+C to stop)")
@@ -305,20 +319,22 @@ defmodule OrgGarden.CLI do
     IO.puts("==> Exporting org files from #{notes_dir}")
 
     case OrgGarden.Export.export_all(notes_dir, output_dir) do
-      {:ok, 0} ->
+      {:ok, 0, []} ->
         IO.puts("  no .org files found")
+        :ok
 
-      {:ok, count} ->
+      {:ok, count, []} ->
         IO.puts("  exported #{count} file(s)")
+        :ok
 
-      {:error, failures} ->
-        IO.puts(:stderr, "\nFailed to export #{length(failures)} file(s):")
+      {:ok, count, failures} ->
+        IO.puts("  exported #{count} file(s), #{length(failures)} failed")
 
-        Enum.each(failures, fn {f, {:error, reason}} ->
-          IO.puts(:stderr, "  #{f}: #{inspect(reason)}")
+        Enum.each(failures, fn {f, {:error, {:emacs_exit, code}}} ->
+          IO.puts(:stderr, "  failed: #{f} (emacs exit code #{code})")
         end)
 
-        System.halt(1)
+        {:error, length(failures)}
     end
   end