docs: Improve tool description with label and relationship type documentation

[greynewell]

Problem

The tool description in src/tools/create-supermodel-graph.ts shows example output with sampleNodes and sampleRelationships, but doesn't explain:

1. What do the labels mean?

   • Function, Class, Type, File, Domain, ExternalModule, LocalModule, etc.

2. What relationship types exist?

   • CHILD_DIRECTORY, CONTAINS_FILE, calls, IMPORTS, etc.

3. What properties are available on each node type?

   • Functions have: filePath, startLine, endLine, language, kind
   • Files have: path, language
   • Domains have: ?

Proposed Enhancement

Add a reference section to the tool description:

## Graph Schema Reference

### Node Types (Labels)
- **Function**: Functions and methods (properties: filePath, startLine, endLine, language, kind)
- **Class**: Class definitions (properties: filePath, startLine, endLine, language)
- **Type**: Type definitions and interfaces (properties: filePath, startLine, endLine, language, kind)
- **File**: Source files (properties: path, filePath, language)
- **Domain**: Architectural domains (properties: name)
- **ExternalModule**: External dependencies (properties: name)
- **LocalModule**: Internal modules (properties: name, filePath)

### Relationship Types
- **CHILD_DIRECTORY**: Directory containment hierarchy
- **CONTAINS_FILE**: Directory contains file
- **calls**: Function calls another function
- **IMPORTS**: File imports from module
- **DEFINES**: File defines a function/class/type
- **MEMBER_OF**: Entity belongs to a domain

Benefits

• Agents understand what data is available
• Better query construction
• Clearer expectations
• Reduced trial-and-error