Add DeepNews as Alert Source and Improve API Documentation

[th0rntwig]

Summary

• Add DeepNews as a new alert source type, enabling deep research capabilities within the alerts system
• Add new AlertType enum for explicit alert behavior configuration
• Improve field descriptions across alert and deepnews DTOs for better API documentation
• Add support for new model claude-opus-4-6 in AlertReportModel

Changes

alert.py

• New DeepNews source: Added DeepNewsSource and DeepNewsSourceParams classes allowing alerts to use DeepNews for deep research with configurable parameters (model, search depth, sources, journalist mode, etc.)
• New AlertType enum: Added Literal["AlertRepeat", "AlertOnce", "ReportRepeat", "ReportOnce"] for explicit control over alert behavior (one-time vs recurring, with or without reports)
• Renamed ReportModel to AlertReportModel: Better naming clarity
• Added claude-opus-4-6 to supported report models
• Added title field to CreateAlertRequest and UpdateAlertRequest
• Made query required in CreateAlertRequest (was optional)
• Improved field descriptions: Enhanced documentation for cron, triggers, sources, model, always_trigger, repeat, and report fields
• Removed filter_params from UpdateAlertRequest (now handled via source params)

deepnews.py

• Added type aliases: DeepNewsSourceType and DeepNewsInlineCitationType for better type reuse
• Added thread_id field: Support for continuing conversations via thread ID
• Added only_cited_sources field: Option to return only sources that are cited in the response
• Improved field descriptions: Enhanced documentation for all request parameters with clearer explanations of their purpose and behavior
• Reordered fields: Logical grouping with research-related fields first, then output formatting, then model parameters

Test plan

• Verify DeepNews can be used as an alert source
• Test AlertType enum values work correctly for different alert behaviors
• Confirm existing alerts continue to work with the updated schema
• Validate API documentation reflects the improved field descriptions