docs(anything-api): document the v2 contract; v1 SSE feed retired - #915

Running Vale across on the following files affected by this PR:

- product/anything-api.mdx
- snippets/anything-api/consume_stream.mdx
- snippets/anything-api/start_detached.mdx

Attempting to initialize Vale linter...
No customer vale configuration detected. Using Mintlify's default configuration.
Attempting to run Vale spellcheck...
Vale spellcheck completed successfully.

docs/src/product/anything-api.mdx:
	- 3:32      Did you really mean 'automations'?
	- 12:65     Did you really mean 'Notte'?
	- 15:85     Did you really mean 'notte'?
	- 180:33    Did you really mean 'Notte'?

docs/src/snippets/anything-api/consume_stream.mdx:
	- 25:1     Did you really mean 'thread_id'?
	- 26:21    Did you really mean 'thread_id'?


Found 6 suggested changes across 2 files in 487.73ms