Summary by cubic

Fixes docs sponsor rendering by safely handling missing tiers and cleaning up docs/data/sponsors.json, preventing homepage and Sponsors pages from breaking across locales.

Description

• Summary of changes
  • Added optional chaining + [] fallbacks in index.md and pages/misc/sponsors.md for en/es/fr/zh.
  • Updated docs/data/sponsors.json: corrected active flags, removed duplicates, added/removed entries, and allowed missing tiers (e.g., platinum) without breaking pages.
• Reasoning
  • Some sponsor arrays were undefined/empty, causing spreads and filters to throw and pages to fail.
• Additional context
  • Stabilizes docs build on fix/docs-build-issues and ensures sponsor sections render even if a tier is absent.

Docs

• Update /docs/ to note that any sponsor tier array may be omitted and the site will default to empty lists. Outline sponsors.json structure and the active flag behavior.

Testing

• No automated tests added.
• Manual verification: build the docs and load the homepage and Sponsors pages for all locales; confirm no errors when a tier is missing and sponsor grids render with only active entries.

Semantic version impact

• No impact to axios packages; docs-only change. No release required.

^{Written for commit 975b7c5. Summary will update on new commits.}