[Hyperdrive] Add best practices guide

[ivoryibu]

Summary

Adds a Hyperdrive best practices guide that consolidates production guidance and routes readers to the detailed source pages.

• Recommends short-lived database clients and direct database endpoints to preserve Hyperdrive pooling behavior.
• Explains conservative pool sizing, short transactions, and metrics to help prevent connection exhaustion.
• Defines cached and cache-disabled query paths to protect freshness and tenant isolation.
• Covers Placement, private connectivity, driver constraints, retries, and runtime lifecycle patterns.

Screenshots (optional)

Documentation checklist

• The change adheres to the documentation style guide.
• If a larger change - such as adding a new page- an issue has been opened in relation to any incorrect or out of date information that this PR fixes.

[github-actions]

This pull request requires reviews from CODEOWNERS as it changes files that match the following patterns:

Pattern	Owners
/src/content/docs/hyperdrive/	@elithrar, @rita3ko, @irvinebroque, @vy-ton, @ivoryibu, @thomasgauvin, @sejoker, @knickish, @cloudflare/product-owners

[github-actions]

Preview URL: https://06b60d6b.preview.developers.cloudflare.com
Preview Branch URL: https://hyperdrive-best-practices.preview.developers.cloudflare.com

Files with changes (up to 15)

Original Link	Updated Link
https://developers.cloudflare.com/hyperdrive/best-practices/	https://hyperdrive-best-practices.preview.developers.cloudflare.com/hyperdrive/best-practices/