test(@angular/cli): add CI validation for MCP example code

[clydin]

This commit introduces a new CI check to validate the correctness of code snippets and markdown structure within the find_examples markdown files.

To support this, the previous the example_db_generator.js script has been refactored and consolidated into a single, unified, mode-driven script: process_examples.mjs. This improves maintainability and ensures consistent parsing and validation logic.

The new script provides two new validation modes for CI:

• validate-structure: Parses all examples to validate their front matter and ensure they adhere to the required markdown heading structure.
• validate-code: Uses a pre-built Angular application harness to perform a full ng build on all example code, ensuring compilation and template correctness.

NOTE: Only the structure checks are enabled within CI at this time.