Fix index.md not being generated

- Generate index even when no .org files are found
- Don't halt CLI early when no org files - let pipeline complete
- Index will be empty but present, allowing Quartz to serve something

lib/org_garden/cli.ex

@@ -306,8 +306,7 @@ defmodule OrgGarden.CLI do
 
     case OrgGarden.Export.export_all(notes_dir, output_dir) do
       {:ok, 0} ->
-        IO.puts("No .org files found in #{notes_dir}")
-        System.halt(0)
+        IO.puts("  no .org files found")
 
       {:ok, count} ->
         IO.puts("  exported #{count} file(s)")

lib/org_garden/server.ex

@@ -150,6 +150,8 @@ defmodule OrgGarden.Server do
     case OrgGarden.Export.export_all(notes_dir, output_dir) do
       {:ok, 0} ->
         Logger.warning("No .org files found in #{notes_dir}")
+        # Still generate index (will be empty or have default content)
+        OrgGarden.Index.generate(content_dir)
         :ok
 
       {:ok, count} ->