docs(upload): add receipts guide flow and verification guidance

[kempsterrrr]

Summary

• add new /build/upload/receipts page
• emphasize timestamp and ordering value
• add deferred verification checklist and example
• move receipts in sidebar to follow manifests
• update cross-links in upload docs

Validation

• npm run lint (passes with one existing unrelated warning)

[github-actions]

Permaweb Preview Deployed

Your preview is available at: https://docs-pr-105_docs.ar.io

Property	Value
Transaction ID	boCUF9MeOG-NPf9b3_eqQ-1FAMR-Bpzb9JmcvbZw1GM
ArNS Name	docs
Undername	docs-pr-105

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[kempsterrrr]

Pushed a follow-up commit to address the latest issues:

• Added Glossary as a proper top-level docs section so it appears in the global section dropdown under APIs Reference.
  • Added content/glossary/meta.json with root: true
  • Moved content/glossary.mdx to content/glossary/index.mdx
  • Kept root ordering in content/meta.json as ... learn, build, sdks, apis, glossary, ...
• Fixed hydration mismatch risk in src/components/page-actions.tsx by removing window access during render-time useMemo and using the provided absolute markdownUrl directly.

Also re-ran lint (passes with the existing unrelated warning in content/build/guides/storing-nfts.mdx).