Update SharePoint Framework JSOM tutorial to heft

[Ashlesha-MSFT]

Category

• Content fix

Related issues

• fixes SPFx Docs Update for Heft toolchain: connect-to-sharepoint-using-jsom.md #10585

What's in this Pull Request?

• Updated 'gulp serve --nobrowser' to 'heft start --nobrowser' (2 instances)
• Standardized error handling with consistent string-based approach
• Improved React component constructor and TypeScript typing
• Enhanced code formatting and readability
• Added proper callout formatting for tenant URL replacement instructions

[learn-build-service-prod]

PoliCheck Scan Report

The following report lists PoliCheck issues in PR files. Before you merge the PR, you must fix all severity-1 and severity-2 issues. The AI Review Details column lists suggestions for either removing or replacing the terms. If you find a false positive result, mention it in a PR comment and include this text: #policheck-false-positive. This feedback helps reduce false positives in future scans.

✅ No issues found

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[learn-build-service-prod]

Learn Build status updates of commit 0847b31:

✅ Validation status: passed

File	Status	Preview URL	Details
docs/spfx/web-parts/guidance/connect-to-sharepoint-using-jsom.md	✅Succeeded	View

For more details, please refer to the build report.