Devlog #17: Validation before sending to TikTok API

The TikTok API strictly limits accepted video formats: file size, duration, codec, resolution. Send the wrong thing and you get an error from the API, and the user sees a cryptic message.

We added a validation layer on the Quedula side before any call to TikTok. We check: file format, size, duration, presence of a description.

This lets us return clear errors to the user before a request even goes out to the external service. "Video is longer than 10 minutes" is far clearer than "API error 10007."

A secondary effect: it reduces the number of "junk" requests to the TikTok API, which matters in the context of rate limits.