Task: Fix Project Configuration Generator

You have a generator that adds a new build target to existing projects, but it's causing major problems:

1. It overwrites the entire project.json, deleting existing targets
2. It adds imports across project boundaries without checking tags
3. Paths are hardcoded to a specific workspace structure

Current Broken Implementation

import { Tree } from '@nx/devkit';
import { writeFileSync } from 'fs';

export default async function (tree: Tree, options: { project: string }) {
  // PROBLEM 1: Overwrites entire config
  const newConfig = {
    name: options.project,
    targets: {
      'custom-build': {
        executor: '@nx/js:tsc',
        options: { outputPath: 'dist/libs/' + options.project }
      }
    }
  };
  
  tree.write(`libs/${options.project}/project.json`, JSON.stringify(newConfig));
  
  // PROBLEM 2: No boundary checks
  tree.write(
    `libs/${options.project}/src/index.ts`,
    `import { util } from '@myorg/internal-api';` // Cross-boundary import!
  );
}

Reported Issues

Issue #1: "The generator deleted all my existing targets!"

• Developer had build, test, and lint targets
• After running generator, only custom-build remains

Issue #2: "CI fails with boundary violation errors"

• Generator adds imports from scope:internal to scope:public libraries
• Nx enforce-module-boundaries rule fails

Issue #3: "Generator breaks when we reorganize folders"

• Hardcoded libs/ prefix fails with different workspace layouts
• Some projects are in packages/, others in libs/

Your Mission

Fix the generator to safely update configurations.

Deliverables

Create:

1. generator.ts - Fixed implementation using proper APIs
2. SAFETY-GUIDE.md - Explain the fixes and why they're necessary

Key Requirements

• Read existing configuration before modifying
• Preserve all existing targets/settings
• Get project path from configuration, not hardcoded
• Verify boundaries before cross-project imports (check tags)

Test Scenario

Existing project config:

{
  "name": "my-lib",
  "root": "packages/libs/my-lib",
  "tags": ["scope:public", "type:util"],
  "targets": {
    "build": { "executor": "@nx/js:tsc" },
    "test": { "executor": "@nx/jest:jest" }
  }
}

Generator should ADD custom-build target while preserving build and test.

Constraints

• No actual workspace files - just the generator code
• Focus on safe config mutations and boundary checking