OpenAI Agents voice support

[tcdent]

Add semantic conventions for voice messages.

Explore options for storing base64 encoded data outside of span attributes.

[bboynton97]

big if true

[tcdent]

@bboynton97 @areibman @teocns

Few options to get this out the door:

• Store the base64 data inside the SpanAttributes
• Don't store the base64 data
• Create a new API endpoint that accepts base64 data and returns a URL to it's location. I would just upload this to S3 and then use the default S3 URL to give the customer a link to their data as a raw blob.

I can create the endpoint and have it deployed today along with the feature in SDK.

[teocns]

@tcdent S3 is the way (supabase buckets for now)

I have created some basis for working with buckets somewhere in legacy APIs and there might even be PRs somewhere (which were showing off how to store logs, but MEDIA is also a fair use case)

also no base64: we're excessively increasing the payload (like x2-3?) when we can just store .raw bytes

[tcdent]

Data already comes base64 encoded and is not processed further before upload.