Fix precompile hook to properly locate Rails root

Add find_rails_root helper that walks upward from current directory
looking for config/environment.rb to locate the Rails root, instead
of assuming the current working directory is the Rails root.

Changes:
- Add find_rails_root() method that searches parent directories
- Returns nil if Rails root cannot be found (reaches filesystem root)
- Update generate_packs_if_needed to use Rails root for all paths
- Build absolute path to config/initializers/react_on_rails.rb

Benefits:
- Works regardless of current working directory
- More robust when hook is called from subdirectories
- Gracefully handles non-Rails environments

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

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

Author: justin808

spec/dummy/bin/shakapacker-precompile-hook

@@ -7,6 +7,19 @@
 
 require "fileutils"
 
+# Find Rails root by walking upward looking for config/environment.rb
+def find_rails_root
+  dir = Dir.pwd
+  loop do
+    return dir if File.exist?(File.join(dir, "config", "environment.rb"))
+
+    parent = File.dirname(dir)
+    return nil if parent == dir # Reached filesystem root
+
+    dir = parent
+  end
+end
+
 # Build ReScript if needed
 def build_rescript_if_needed
   # Check for both old (bsconfig.json) and new (rescript.json) config files
@@ -36,11 +49,18 @@ def build_rescript_if_needed
 end
 
 # Generate React on Rails packs if needed
+# rubocop:disable Metrics/CyclomaticComplexity
 def generate_packs_if_needed
-  return unless File.exist?("config/initializers/react_on_rails.rb")
+  # Find Rails root directory
+  rails_root = find_rails_root
+  return unless rails_root
+
+  # Check if React on Rails initializer exists
+  initializer_path = File.join(rails_root, "config", "initializers", "react_on_rails.rb")
+  return unless File.exist?(initializer_path)
 
   # Check if auto-pack generation is configured (match actual config assignments, not comments)
-  config_file = File.read("config/initializers/react_on_rails.rb")
+  config_file = File.read(initializer_path)
   has_auto_load = config_file =~ /^\s*config\.auto_load_bundle\s*=/
   has_components_subdir = config_file =~ /^\s*config\.components_subdirectory\s*=/
   return unless has_auto_load || has_components_subdir
@@ -65,6 +85,7 @@ def generate_packs_if_needed
     exit 1
   end
 end
+# rubocop:enable Metrics/CyclomaticComplexity
 
 # Main execution
 begin