Add new dependencyGraph category (3 endpoints)

[ldraney]

Parent Issue

#86 — Expand Octokit coverage

Category: dependencyGraph (NEW — no file exists yet)

File to create: src/tools/categories/dependencyGraph.ts

Methods to Add (3)

Method	Route
createRepositorySnapshot	POST /repos/{owner}/{repo}/dependency-graph/snapshots
diffRange	GET /repos/{owner}/{repo}/dependency-graph/compare/{basehead}
exportSbom	GET /repos/{owner}/{repo}/dependency-graph/sbom

Setup Required

1. Create src/tools/categories/dependencyGraph.ts following the pattern in git.ts
2. Export dependencyGraphCategory from src/tools/categories/index.ts
3. Add to ALL_CATEGORIES in src/tools/generator.ts
4. Add to full preset and security preset in generator.ts

Pattern

import type { ToolCategory } from '../types.js';
import { successResult } from '../types.js';

export const dependencyGraphCategory: ToolCategory = {
  name: 'dependencyGraph',
  description: 'Dependency graph operations including SBOM export and dependency snapshots',
  tools: [
    // ... tool definitions
  ],
};

Tool name format: github_dependency_graph_<snake_case_method>.

Acceptance Criteria

• New file created with all 3 methods
• Exported from index.ts
• Registered in generator.ts (ALL_CATEGORIES + presets)
• npm run build passes
• TOOLS.md updated