Professionalize repository and sanitize demo data

[ZOB2077]

Summary

• replace the starter-pack README with a user-facing product page
• add CI, issue forms, a pull request template, contribution guidance, security policy, support policy, and changelog
• align product and release documentation with the office formula-bar and floating-reader experience
• set the application version to 0.1.0 (1)
• replace embedded business-looking table rows with deterministic synthetic demo fixtures

Validation

• 48 unit tests passed with UI automation intentionally excluded from unattended runs
• release app built and ad-hoc signature verified
• ZIP integrity and DMG checksum verified
• packaged binary scanned for the removed legacy business identifiers
• workflow YAML and local Markdown links validated

Privacy

No spreadsheet screenshots, source workbooks, or real business records are included. Built-in office tables are generated synthetic data.