docs: add hidden self-hosted async transcription documentation

[devin-ai-integration]

docs: add hidden self-hosted async transcription documentation

Summary

Added a new hidden documentation page for the self-hosted async transcription solution based on instructions from the Slack thread. The documentation covers:

• System requirements (GPU, Docker, AWS ECR access)
• Setup and deployment steps (NVIDIA drivers, container toolkit, ECR authentication)
• Docker container configuration with license file
• API usage (health check and transcription endpoints)
• Troubleshooting common issues
• Note about simplified installation being in development

The page is configured as hidden (not shown in navigation but accessible via direct URL) following the same pattern as the existing self-hosted streaming documentation.

Review & Testing Checklist for Human

• Verify technical accuracy: Confirm all Docker commands, ECR URLs (344839248844.dkr.ecr.us-west-2.amazonaws.com/self-hosted-ml-prod:release-v0.1), and API endpoints (/health, /predict) match the actual implementation
• Check API request/response formats: The example JSON response structure was inferred - verify it matches what the container actually returns
• Validate language support: Confirm the listed language codes are accurate for this self-hosted solution
• Test hidden doc accessibility: Verify the page is accessible via direct URL but not shown in the navigation menu (similar to self-hosted streaming doc)
• Review license file details: Confirm the 30-day testing limitation and license file requirements are correct

Test Plan

1. Navigate to the docs site and verify the "Self-hosted async" page is NOT visible in the navigation
2. Access the page directly via URL to confirm it renders correctly
3. Review the content with someone familiar with the self-hosted async solution (Tomas or the team) to verify technical accuracy

Notes

• This documentation was created based on Slack thread instructions from Tomas Urbonaitis about the Calabrio integration
• The "Simplified installation" section is intentionally vague as this is still in development per the Slack conversation
• Pre-existing lint errors in openapi.yml and asyncapi.yml are unrelated to this documentation change

Link to Devin run: https://app.devin.ai/sessions/153e1b48e3814da7940b08c7b989ee75
Requested by: Ryan Seams (@ryanseams)

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