Improve file upload UX with validation and uploaded files display

Enhanced the benefit forms file upload functionality to provide better
user feedback and visibility of uploaded files.

Changes:
1. Added file type validation in controller:
   - Only accepts PDF, DOC, DOCX, JPG, PNG formats
   - Shows clear error message with the rejected file extension

2. Added file size validation:
   - Maximum 10MB file size limit
   - Shows file size in error message if exceeded

3. Improved success/error messages:
   - Shows specific filename on successful upload
   - Shows detailed error messages for validation failures

4. Added uploaded files display section:
   - Lists all uploaded files with icons based on file type
   - Shows file size and upload timestamp
   - Provides download button for each file
   - Only displays when files exist

Before: Users received generic "Something went wrong" message with no
indication of why uploads failed. No way to see uploaded files.

After: Clear validation feedback tells users exactly what went wrong
(wrong format, too large, etc.) and uploaded files are visible with
download links.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/controllers/benefit_forms_controller.rb

@@ -3,6 +3,15 @@ class BenefitFormsController < ApplicationController
 
   def index
     @benefits = Benefits.new
+    # List uploaded files
+    data_path = Rails.root.join("public", "data")
+    @uploaded_files = Dir.glob("#{data_path}/*").reject { |f| File.directory?(f) || File.basename(f) == '.gitkeep' }.map do |file|
+      {
+        name: File.basename(file),
+        size: File.size(file),
+        modified: File.mtime(file)
+      }
+    end.sort_by { |f| f[:modified] }.reverse
   end
 
   def download
@@ -17,12 +26,38 @@ class BenefitFormsController < ApplicationController
 
   def upload
     file = params[:benefits][:upload]
-    if file
-      flash[:success] = "File Successfully Uploaded!"
-      Benefits.save(file, params[:benefits][:backup])
-    else
-      flash[:error] = "Something went wrong"
+
+    if file.nil?
+      flash[:error] = "Please select a file to upload"
+      redirect_to user_benefit_forms_path(user_id: current_user.id)
+      return
     end
+
+    # Validate file type
+    allowed_extensions = %w[.pdf .doc .docx .jpg .jpeg .png]
+    file_extension = File.extname(file.original_filename).downcase
+
+    unless allowed_extensions.include?(file_extension)
+      flash[:error] = "Invalid file type. Accepted formats: PDF, DOC, DOCX, JPG, PNG. You uploaded: #{file_extension}"
+      redirect_to user_benefit_forms_path(user_id: current_user.id)
+      return
+    end
+
+    # Validate file size (10MB max)
+    max_size = 10.megabytes
+    if file.size > max_size
+      flash[:error] = "File too large. Maximum size: 10MB. Your file: #{(file.size / 1.megabyte.to_f).round(2)}MB"
+      redirect_to user_benefit_forms_path(user_id: current_user.id)
+      return
+    end
+
+    begin
+      Benefits.save(file, params[:benefits][:backup])
+      flash[:success] = "File '#{file.original_filename}' uploaded successfully!"
+    rescue => e
+      flash[:error] = "Failed to upload file: #{e.message}"
+    end
+
     redirect_to user_benefit_forms_path(user_id: current_user.id)
   end