fix(@angular/cli): add schema versioning and metadata to example database

[clydin]

This commit introduces schema versioning and metadata to the Angular CLI's example database.

A new metadata table has been added to both the runtime and build-time example databases. This table stores key-value pairs, initially including schema_version and created_at.

The find_examples tool now validates the schema_version of the loaded database. If a schema mismatch is detected, the tool throws a descriptive error message that guides the user on how to resolve the incompatibility (e.g., by updating their CLI or project's @angular/core package).

This change improves the robustness and maintainability of the example database by:

• Ensuring compatibility between the CLI and the example database schema.
• Providing actionable feedback to users when schema versions are incompatible.
• Laying the groundwork for future metadata additions and database evolution.

[clydin]

This PR was merged into the repository. The changes were merged into the following branches:

• main: a9acc2e
• 21.0.x: c17d7a9

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}