Add unit tests and examples for heart.csv and loans_payments.csv datasets

[Copilot]

Adds test coverage and usage examples for the heart disease and loan payments datasets in the data directory.

Changes

Tests (__tests__/ava.test.ts)

• New test suite for heart.csv with 4 tests covering age distribution, gender analysis, disease prevalence, and cholesterol levels
• Follows existing pattern: parent beforeEach for AVA instance, nested beforeEach for CSV loading

Examples

• examples/heart-disease-analysis.ts - Demonstrates queries for patient demographics and health metrics
• examples/loan-payments-analysis.ts - Demonstrates queries for loan status, education levels, and borrower demographics
• examples/companies-analysis.ts - Renamed from basic-usage.ts and updated header comment for naming consistency

All three examples follow a consistent naming pattern (<dataset>-analysis.ts) with 4 representative queries each.

// Example usage
const ava = new AVA({ llm: getLLMConfig() });
await ava.loadCSV('../data/heart.csv');
const result = await ava.analysis('What is the average age of patients?');

Original prompt

1. 针对 data/heart.csv 数据，在 ava.test.ts 中添加一些合适的单测。
2. 在 examples 中，增加对 data/heart.csv 和 data/loans_payments.csv 的示例。

保持代码简洁精炼。

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[hustcc]

@copilot examples/basic-usage.ts 改名 examples/companies-analysis.ts，保持统一。

[Copilot]

@copilot examples/basic-usage.ts 改名 examples/companies-analysis.ts，保持统一。

Done. Renamed to companies-analysis.ts in commit 8b71edf.