Teach result exports and downstream analysis #116

Affected library: backtest
Current version: 0.1.8
Location: results and analysis tutorial

Problem

The result API has several exports, but users lack one worked path to reconcile equity, trades, fills, returns, portfolio state, and funding or to join results back to their input data.

Required outcome

Show result inspection and artifact round trips on a time-zone-aware feed, then a supported handoff to ml4t-diagnostic for analysis. Declare any optional dependency for the final step and link to the book's performance-reporting material.

Acceptance criteria

• Result timestamps join to feed and prediction timestamps without user-side zone casts.
• Exports and artifact round trips preserve documented event meaning.
• The downstream analysis executes under its declared dependency set.
• Installed-wheel checks and the strict MkDocs build pass.

Depends on the timestamp-export and funding issues and shared tutorial inputs.