fix: Correct ticket creation flow and home page availability check

- Fix incorrect route helper in tickets controller (order_checkout_path -> checkout_order_path)
- Add missing set_event before_action for create action
- Fix home page availability check to use ticket_types.available_quantity instead of tickets.quantity
- Update AGENT.md with ast-grep documentation for development tools

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

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

AGENT.md

@@ -256,6 +256,38 @@ events = Event.create!([...])
 ticket_types = TicketType.create!([...])
 ```
 
+## 🛠️ Available Development Tools
+
+### AST-Grep for Mass Code Replacement
+
+The system has `ast-grep` installed for structural code search and replacement. This tool is particularly useful for:
+
+- **Mass refactoring**: Rename methods, classes, or variables across the codebase
+- **Pattern-based replacements**: Update code patterns using AST matching
+- **Language-aware transformations**: Safer than regex for code modifications
+
+#### Usage Examples:
+
+```bash
+# Find all method calls to a specific method
+ast-grep --pattern 'find_by_$FIELD($VALUE)' --lang ruby
+
+# Replace method calls with new syntax
+ast-grep --pattern 'find_by_$FIELD($VALUE)' --rewrite 'find_by($FIELD: $VALUE)' --lang ruby
+
+# Search for specific Rails patterns
+ast-grep --pattern 'validates :$FIELD, presence: true' --lang ruby
+
+# Mass rename across multiple files
+ast-grep --pattern 'old_method_name($$$ARGS)' --rewrite 'new_method_name($$$ARGS)' --lang ruby --update-all
+```
+
+#### Best Practices:
+- Always run with `--dry-run` first to preview changes
+- Use `--lang ruby` for Ruby files to ensure proper AST parsing
+- Test changes in a branch before applying to main codebase
+- Particularly useful for Rails conventions and ActiveRecord pattern updates
+
 ## 📝 Code Style & Conventions
 
 - **Ruby Style**: Follow Rails conventions and Rubocop rules
@@ -263,5 +295,6 @@ ticket_types = TicketType.create!([...])
 - **JavaScript**: Stimulus controllers for interactive behavior
 - **CSS**: Tailwind utility classes with custom components
 - **Documentation**: Inline comments for complex business logic
+- **Mass Changes**: Use `ast-grep` for structural code replacements instead of simple find/replace
 
 This architecture provides a solid foundation for a scalable ticket selling platform with proper separation of concerns, security, and user experience.