feat: Move email attachments from links to file attachments (#11304)

Add ability to send files as attachments instead of links
Fixes: https://github.com/chatwoot/chatwoot/issues/1074


## Changes 
- `emaily_reply` : We will attach the small attachments as attachments
and large ones as links
- `reply_with_summary`, `conversation_transcript`,
`reply_with_out_summary` : We will change the attachment format to the
following instead of the previous `View the attachment here`

```
Attachments:
file_name
file_name2
```


---------

ref: https://github.com/chatwoot/chatwoot/pull/10318/files -> for fixing
: https://github.com/chatwoot/chatwoot/pull/9655#issuecomment-2183962550

---------

Co-authored-by: Marco Marinho <marcomarinho12@gmail.com>
Co-authored-by: Pranav <pranavrajs@gmail.com>

app/mailers/conversation_reply_mailer.rb

@@ -1,4 +1,8 @@
 class ConversationReplyMailer < ApplicationMailer
+  # We needs to expose large attachments to the view as links
+  # Small attachments are linked as mail attachments directly
+  attr_reader :large_attachments
+
   include ConversationReplyMailerHelper
   default from: ENV.fetch('MAILER_SENDER_EMAIL', 'Chatwoot <accounts@chatwoot.com>')
   layout :choose_layout

app/mailers/conversation_reply_mailer_helper.rb

@@ -17,11 +17,44 @@ module ConversationReplyMailerHelper
     google_smtp_settings
     set_delivery_method
 
-    Rails.logger.info("Email sent from #{email_from} to #{to_emails} with subject #{mail_subject}")
-
+    # Email type detection logic:
+    # - email_reply: Sets @message with a single message
+    # - Other actions: Set @messages with a collection of messages
+    #
+    # So this check implicitly determines we're handling an email_reply
+    # and not one of the other email types (summary, transcript, etc.)
+    process_attachments_as_files_for_email_reply if @message&.attachments.present?
     mail(@options)
   end
 
+  def process_attachments_as_files_for_email_reply
+    # Attachment processing for direct email replies (when replying to a single message)
+    #
+    # How attachments are handled:
+    # 1. Total file size (<20MB): Added directly to the email as proper attachments
+    # 2. Total file size (>20MB): Added to @large_attachments to be displayed as links in the email
+
+    @options[:attachments] = []
+    @large_attachments = []
+    current_total_size = 0
+
+    @message.attachments.each do |attachment|
+      raw_data = attachment.file.download
+      attachment_name = attachment.file.filename.to_s
+      file_size = raw_data.bytesize
+
+      # Attach files directly until we hit 20MB total
+      # After reaching 20MB, send remaining files as links
+      if current_total_size + file_size <= 20.megabytes
+        mail.attachments[attachment_name] = raw_data
+        @options[:attachments] << { name: attachment_name }
+        current_total_size += file_size
+      else
+        @large_attachments << attachment
+      end
+    end
+  end
+
   private
 
   def google_smtp_settings