feat: Add GitHub Action to auto-sync wiki from a /docs (or /wiki) folder in the repository

[Ma77Ball]

What changes were proposed in this PR?

This PR adds a GitHub Actions workflow (.github/workflows/sync-wiki.yml) that automatically syncs the contents of a docs/wiki/ folder in the main repository to the GitHub wiki on every push to main.
Before: Wiki pages could only be edited by project committers with direct write access to the GitHub wiki, making documentation contributions impossible via the standard PR process.
After: Any contributor can open a PR modifying markdown files under docs/wiki/, and upon merge the wiki is updated automatically. This mirrors the exact structure of the existing wiki — filenames map directly to wiki page names.
Changes included:

New workflow file: .github/workflows/sync-wiki.yml
New folder: docs/wiki/ seeded with the current wiki content as a baseline

Any related issues, documentation, discussions?

Resolves #4258

How was this PR tested?

The workflow was tested by pushing a change to a file in docs/wiki/ on a fork with wiki enabled and confirming the target wiki page updated correctly after the Action completed. No unit tests apply to this change as it is purely CI/CD infrastructure. The Action itself (Andrew-Chen-Wang/github-wiki-action) is a well-maintained open source action with its own test coverage.
Manual verification steps:

Fork the repo and enable the wiki on the fork
Add WIKI_PUSH_TOKEN as a repo secret (or confirm GITHUB_TOKEN has wiki write permissions)
Merge a small edit to a file in docs/wiki/
Confirm the corresponding wiki page reflects the change

Was this PR authored or co-authored using generative AI tooling?

Reviewed by Claude

[Ma77Ball]

@chenlica or @bobbai00, please review.

[chenlica]

@Ma77Ball Let's have a discussion then report the finding in this PR.