fix: stream attachment handling in workers (#12870)

We’ve been watching Sidekiq workers climb from ~600 MB at boot to
1.4–1.5 GB after an hour whenever attachment-heavy jobs run. This PR is
an experiment to curb that growth by streaming attachments instead of
loading the whole blob into Ruby: reply-mailer inline attachments,
Telegram uploads, and audio transcriptions now read/write in chunks. If
this keeps RSS stable in production we’ll keep it; otherwise we’ll roll
it back and keep digging

enterprise/app/services/captain/llm/pdf_processing_service.rb

@@ -29,12 +29,16 @@ class Captain::Llm::PdfProcessingService < Llm::LegacyBaseOpenAiService
     end
   end
 
-  def with_tempfile(&)
+  def with_tempfile
     Tempfile.create(['pdf_upload', '.pdf'], binmode: true) do |temp_file|
-      temp_file.write(document.pdf_file.download)
-      temp_file.close
+      document.pdf_file.blob.open do |blob_file|
+        IO.copy_stream(blob_file, temp_file)
+      end
 
-      File.open(temp_file.path, 'rb', &)
+      temp_file.flush
+      temp_file.rewind
+
+      yield temp_file
     end
   end
 end