Upload modes: docs-site reference + recipes + nav (post-release)

[adnaan]

Follow-up from the upload-modes example (livetemplate#447).

The runnable example landed (examples/upload-modes/), but the docs-site content still needs updating to the four-mode Mode API. This is gated on the livetemplate + client release that ships upload modes (so go.mod can bump to it).

Tasks

• Rewrite content/reference/uploads.md around the four modes (Volume default / Direct / Proxied / Preview), mirroring the library's docs/references/uploads.md.
• Update content/recipes/ui-patterns/forms/file-upload.md and content/recipes/apps/avatar-upload.md to the Mode API.
• Add a recipe content/recipes/apps/upload-modes.md pointing at the example.
• Register new pages in content/tinkerdown.yaml nav.
• Run cmd/sync so example snippets stay in lockstep with the code.

[adnaan]

PR #74 covers 3 of the 5 tasks here — recipes (avatar-upload, new upload-modes, file-upload), nav registration, and the go.mod bump to v0.13.0.

The other two — rewriting content/reference/uploads.md and running cmd/sync — landed via the v0.13.0 sync PRs #72 (livetemplate) + #73 (client), now merged. Superseded sync PRs #69/#70/#54 closed.

Close this issue after #74 merges. One leftover, tracked separately: the upload-modes example's browser E2E (gated by LVT_UPLOAD_MODES_E2E) still isn't wired into docs CI — suggest a dedicated follow-up issue.

[adnaan]

Closed as completed — all tasks landed:

• docs(uploads): four-mode upload recipes + nav (#67) #74 — recipes (avatar-upload, new upload-modes, file-upload), nav registration, and the v0.13.0 go.mod bump (merged).
• Sync from livetemplate@v0.13.0 #72 / Sync from client@v0.13.0 #73 — mirrored content/reference/uploads.md + cmd/sync regeneration at v0.13.0 (merged). Superseded sync PRs Sync from livetemplate@v0.12.0 #69/Sync from client@v0.12.0 #70/Sync from client@v0.11.9 #54 closed.

One sub-task split out to a follow-up: wiring the upload-modes example's gated browser E2E into docs CI — #77.