Repo: add Quiveld independent-project directory link to both READMEs

[RXY712200]

Scope

Repo-owned documentation only: add a neutral external navigation link to the author's Quiveld independent-project directory in the English and Chinese root READMEs.

• Link: https://quiveld.com/projects/independent/
• No claims that Quiveld is the official Full/Mini documentation, release source, or dedicated LayerKeySort homepage.
• Full/Mini production sources, CI, governance, tags and releases are untouched.

Evidence

• Started from main ff0012bd6c7c904266926803b5e7f02a6749a6a9.
• Compared branch against base: only README.md and README.zh-CN.md; four added lines each, zero deletions.
• The external page could not be fetched or indexed through available tools in this review, so its current content/HTTP response is not verified. This PR intentionally remains Draft pending URL/page-content check and normal required CI.

Acceptance

• Confirm the external page is the intended author-maintained directory and the link resolves.
• Required full-gate, mini-gate, workbench-gate, scope-guard pass on exact PR head.
• Review and merge only after those conditions; do not bypass the existing ruleset.