docs(cryptify): document HTTP Range support on /filedownload

[dobby-coder]

Closes #85

Summary

Documents the new Range / Accept-Ranges behaviour on cryptify's GET /filedownload/{uuid} introduced by encryption4all/cryptify#154 (merged at b1eff690ea).

• docs/repos/cryptify.md: cross-links the existing API bullet to a new "Range support on /filedownload" subsection covering the four response shapes (200 full, 206 partial, 416 unsatisfiable/multi-range), notes Range joining the CORS allowlist alongside Authorization, Content-Type, Content-Range, CryptifyToken, and X-Recovery-Token.
• docs/guide/architecture.md: extends the Cryptify endpoint-table row for /filedownload/{uuid} with a one-sentence summary and a link into the cryptify page subsection.

Source link pinned to the cryptify merge commit (b1eff690ea...src/main.rs#L959-L1083).

Verification

• npx vitepress build docs succeeds (~6s, mermaid still renders).
• Spot-checked rendered docs/.vitepress/dist/repos/cryptify.html and dist/guide/architecture.html; new anchor #range-support-on-filedownload resolves.
• Style: no em dashes, no banned words, no bold, no significance inflation.

Reviewer quickstart

git fetch origin && git checkout docs/85-cryptify-range-support && npm install && npx vitepress build docs

[dobby-coder]

Self-review (cannot --approve own PR). Verified end-to-end:

• Source link src/main.rs#L959-L1083 at b1eff690ea returns 200; snippet matches the documented behavior: Accept-Ranges: bytes on every response, parse_range_header supports bytes=N-M, bytes=N-, and bytes=-N (open-ended/suffix clamped to file size), multi-range returns None so the caller emits 416, unsatisfiable path sets Content-Range: bytes */total.
• npx vitepress build docs succeeds (~6.5s). Rendered dist/repos/cryptify.html and dist/guide/architecture.html both contain the range-support-on-filedownload anchor.
• Style conforms: no banned words, no em dashes, no bold, no significance inflation.
• Architecture-page row stays one sentence and links into the cryptify subsection, consistent with the upload-limits / auth cross-references.

Ready to merge from this agent's perspective.