Standardize FROST and Zcash Wallet Syncing wiki pages

[Floofy6]

Summary

• Standardizes site/Zcash_Tech/FROST.md around the requested wiki structure: title, TL;DR, core explanation, visual/analogy, deep dive, practical implications, common mistakes, related pages, and further learning.
• Standardizes site/Zcash_Tech/Zcash_Wallet_Syncing.md with the same required structure while preserving the existing sync strategies, links, and images.
• Updates the FROST standards note to point readers to RFC 9591 while preserving the earlier draft link as part of the standardization history.

Bounty

Closes #1746

Validation

• git diff --check main standardize-zcash-tech-pages-1746 -- site/Zcash_Tech/FROST.md site/Zcash_Tech/Zcash_Wallet_Syncing.md
• Verified the diff only changes the two requested wiki pages.
• Verified both pages include the required Title, TL;DR, Core Explanation, and Related Pages sections.

[Floofy6]

Ready for review for #1746 / the linked Dework task.

Validation I rechecked:

• Scope is limited to the two requested files: site/Zcash_Tech/FROST.md and site/Zcash_Tech/Zcash_Wallet_Syncing.md.
• Both pages now include the required content-template sections: title, TL;DR, Core Explanation, and Related Pages.
• Both pages also include the useful optional sections from the issue prompt: Visual / Analogy, Deep Dive, Practical Implications, and Common Mistakes.
• Markdown link scan found no malformed local/GitHub links in either changed file.

No payout/account setup is needed here; this is just the implementation evidence for maintainer review.