Fix bin/dev pack generation failure when run from Bundler context

When bin/dev loads bundler/setup and then PackGenerator tries to run
"bundle exec rake", it fails due to Bundler path conflicts. The system
command tries to spawn a new bundle process from within an already-setup
Bundler environment, causing Ruby/Bundler version mismatches.

Solution: Detect if we're already in a Bundler context and directly
invoke the Rake task instead of shelling out to "bundle exec rake".
This avoids the nested Bundler issue while maintaining compatibility
with non-Bundler environments.

Changes:
- lib/react_on_rails/dev/pack_generator.rb:
  - Add run_pack_generation method to detect Bundler context
  - Add run_rake_task_directly to invoke Rake task in-process
  - Add run_via_bundle_exec for non-Bundler environments
  - Load Rails environment when needed for in-process execution

Fixes: bin/dev static (and other bin/dev commands) now successfully
generate packs before starting the development server.

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

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

Author: justin808

lib/react_on_rails/dev/pack_generator.rb

@@ -9,10 +9,10 @@ class << self
         def generate(verbose: false)
           if verbose
             puts "📦 Generating React on Rails packs..."
-            success = system "bundle exec rake react_on_rails:generate_packs"
+            success = run_pack_generation
           else
             print "📦 Generating packs... "
-            success = system "bundle exec rake react_on_rails:generate_packs > /dev/null 2>&1"
+            success = run_pack_generation(silent: true)
             puts success ? "✅" : "❌"
           end
 
@@ -21,6 +21,56 @@ def generate(verbose: false)
           puts "❌ Pack generation failed"
           exit 1
         end
+
+        private
+
+        def run_pack_generation(silent: false)
+          # If we're already inside a Bundler context (e.g., called from bin/dev),
+          # we can directly require and run the task. Otherwise, use bundle exec.
+          if defined?(Bundler)
+            run_rake_task_directly(silent: silent)
+          else
+            run_via_bundle_exec(silent: silent)
+          end
+        end
+
+        def run_rake_task_directly(silent: false)
+          require "rake"
+
+          # Load Rails environment if not already loaded
+          require File.expand_path("config/environment", Dir.pwd) unless defined?(Rails)
+
+          Rake::Task.clear
+          Rails.application.load_tasks unless Rake::Task.task_defined?("react_on_rails:generate_packs")
+
+          if silent
+            original_stdout = $stdout
+            original_stderr = $stderr
+            $stdout = StringIO.new
+            $stderr = StringIO.new
+          end
+
+          begin
+            Rake::Task["react_on_rails:generate_packs"].invoke
+            true
+          rescue StandardError => e
+            warn "Error generating packs: #{e.message}" unless silent
+            false
+          ensure
+            if silent
+              $stdout = original_stdout
+              $stderr = original_stderr
+            end
+          end
+        end
+
+        def run_via_bundle_exec(silent: false)
+          if silent
+            system "bundle exec rake react_on_rails:generate_packs > /dev/null 2>&1"
+          else
+            system "bundle exec rake react_on_rails:generate_packs"
+          end
+        end
       end
     end
   end