Add curated TradingView indicator features to exported datasets

[sybapp]

Parent

• PRD: ES TradingView-to-Nautilus strategy evolution system #1

What to build

Extend the TradingView Collector export path so a curated indicator allowlist can contribute indicator plots and graphics as typed Structural Features in the Versioned Dataset. This should turn TradingView study periods and study graphics into feature records that can later be consumed by Strategy Specs and Nautilus Validation.

The slice should prove that plots, labels, lines, boxes, and profile-like graphics can be normalized with event time, availability time, feature type, value payload, and repainting-risk metadata.

Acceptance criteria

• A first curated indicator allowlist is represented in dataset metadata.
• Indicator plot values can be exported as feature records.
• Indicator graphics can be exported as typed Structural Features rather than screenshots.
• Every feature record includes event time and availability time.
• Repainting-risk features are marked explicitly and are not exposed as confirmed signals before their availability time.
• The exported dataset passes the Versioned Dataset Contract validator.
• Tests cover confirmed features and repainting-risk features using deterministic fixture data.

Blocked by

• Define and validate the Versioned Dataset Contract #2
• Export a minimal ES RTH 5m dataset from TradingView #3