feat(text chat): add typed video content blocks

[octo-patch]

Reason: Add MiniMax-M3 video content blocks to typed text chat requests.

Changes

• Add URL and base64 video sources to the Messages API content-block types.
• Preserve video detail, frame sampling, and maximum-dimension options in chat payloads.
• Verify that the text SDK sends a complete video block to the chat endpoint.

Checks

• bun test test/sdk/text.test.ts
• bun run typecheck
• bun run lint
• git diff --check

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