Media Upload Progress & Large File Errors

Issue

• Upload progress stayed at 0/100 because progress mutations targeted the raw uploadItems array instead of the reactive uploadQueue.
• Large video uploads (>~100MB) failed with a Cloudflare 413 / network error.

Fix

• Progress, completion, and error states now mutate through uploadQueue.value (matched by id) so the UI updates.
• xhr.onload maps HTTP 413 to a clear "file too large" message.

Limitation

Production is behind Cloudflare, which caps proxied uploads at ~100MB. Files larger than that need direct-to-storage (S3/R2) or chunked upload.

Chunked Upload

Files larger than 20MB are uploaded in 8MB chunks to /api/v1/assets/chunk, which assembles them server-side. This bypasses per-request size limits (e.g. Cloudflare 100MB).