Implement comprehensive Tree-sitter grammar for Structurizr DSL with full language support

[Copilot]

This PR significantly expands the existing Tree-sitter grammar for Structurizr DSL to support the complete language specification, enabling comprehensive syntax highlighting, code navigation, and language tooling.

What's Changed

The previous grammar implementation was minimal, only supporting basic workspace definitions, variables, and simple comments. This implementation adds support for all major Structurizr DSL constructs:

Core Language Features Added

• Model definitions with complete element hierarchy (people, software systems, containers, components)
• Enterprise and group definitions for organizing model elements
• Relationships between elements with properties and styling
• Views definitions including system landscape, system context, container, component, and deployment views
• Deployment environments with deployment nodes and container instances
• Documentation sections and architecture decision records
• Styles definitions for customizing element and relationship appearance
• Include statements and identifiers directive support

Grammar Improvements

• Fixed grammar conflicts and compilation issues
• Added proper node types for all language constructs
• Implemented comprehensive test coverage with corpus files
• Enhanced comment parsing for both single-line (#, //) and multi-line (/* */) comments
• Added variable substitution support with ${variable} syntax

Example Usage

The grammar now successfully parses complex Structurizr DSL files like this:

workspace "Banking System" {
    model {
        user = person "Customer" "Bank customer"
        
        enterprise "Big Bank" {
            system = softwareSystem "Banking System" {
                web = container "Web App" "Frontend" "React"
                api = container "API" "Backend" "Node.js"
                db = container "Database" "Storage" "PostgreSQL"
            }
        }
        
        user -> system "Uses"
        web -> api "Calls"
        api -> db "Stores data"
    }
    
    views {
        systemContext system "Context" {
            include *
            autoLayout
        }
        
        styles {
            element "Person" {
                shape Person
                background #08427b
            }
        }
    }
}

Documentation and Testing

• Added comprehensive README.md with usage examples, installation instructions, and editor integration guides
• Created extensive test corpus covering all language constructs
• Included working example demonstrating core functionality
• Grammar compiles without conflicts and parses real-world DSL files correctly

Language Tooling Support

This implementation enables:

• Syntax highlighting in editors with Tree-sitter support
• Code navigation and folding
• Language server protocol integration
• Static analysis and linting capabilities
• Automatic formatting and refactoring tools

The grammar follows Tree-sitter best practices and provides proper node types for all language constructs, making it suitable for building comprehensive language tooling for Structurizr DSL.

This pull request was created as a result of the following prompt from Copilot chat.

Implement a Tree-sitter grammar for Structurizr DSL. The grammar should:

• Define the syntax for the core Structurizr DSL constructs (workspace, model, views, documentation, deployment, etc).
• Support nested elements and relationships as found in Structurizr DSL (e.g., containers, components, relationships, etc).
• Provide node types for entities, relationships, keywords, and comments.
• Include a grammar.js file describing the language in Tree-sitter format.
• Add a README.md for the grammar with usage and build instructions.
• Provide test cases and corpus files to verify parsing of common Structurizr DSL documents.
• Organize the grammar in a new directory (e.g., tree-sitter-structurizr/) in the repository.

The implementation should enable Tree-sitter parsing for Structurizr DSL source files and lay the foundation for syntax highlighting, diagnostics, and language tooling.

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