Support blob type visualization

[dentiny]

Closes #3

Hi team, since lance file format specializes for multi-model support, in this PR I want to add inline visualization for blob-type data, including videos, images, audios, etc.

In simple words, the backend detects media formats from binary signatures and returns MIME metadata with a base64 payload. The frontend renders recognized values as inline images, audio, or video.

Example UI display

Followup items

• Since multi-modal data is significantly larger than scalar ones, it introduces non-trivial latency overhead; in the followup PR I will introduce UI and IO optimizations, mainly includes (1) parallel IO operations; (2) lazy load blob data
• I have implemented the optimization in my fork https://github.com/dentiny/lance-data-viewer, and deployed to prod inside my workplace

AI usage disclaimer:
GPT-5.5 helped me make the code change, I deployed my own fork to k8s and verified it worked

[gordonmurray]

Thanks for implementing media detection and inline previews. This is a useful direction for issue #3, but I’m requesting changes before merge.

I need to define the binary/media response contract before this implementation can land. The viewer must not embed arbitrary-size images, audio, or video as base64 in every /rows response. That would make large binary datasets substantially slower and could worsen the existing large-payload problem. Browser-side loading="lazy" does not avoid transferring the base64 data already present in the JSON response.

The intended design should be:

• small media may be returned inline under a documented size limit;
• larger media returns metadata only, without a base64 payload;
• loading large media happens through an explicit, bounded/lazy request or user action;
• the API contract clearly distinguishes media metadata from inline content.

I’ll follow up with the exact size limit and endpoint contract. After that, please revise the implementation and add:

• API-level tests for small and oversized media values;
• compatibility tests for ordinary and fixed-size binary columns;
• the media response contract in docs/spec.md;
• the required [Unreleased] CHANGELOG.md entry referencing issue #3.

The preview UX is beneficial, but the current eager full-payload behavior is not safe to merge.

[dentiny]

Hi @gordonmurray thanks for the feedback!

On inline storage fetch vs extra access, I'm thinking whether we could

• Display the blob inline, if the lance blob storage type is storing it inline (instead of packed or URL)
• For large blobs, we (1) display metadata on the blob (i.e., size) and a button; (2) when button clicked by user, fetch the externally stored blob and pop out a separate session to display