Update repository front page

[ranade-oss]

What changed

• Reworked the README around the ROSS product identity and approved Ontario-first positioning.
• Added prominent links to the public beta, project website, service status, documentation, and private security reporting.
• Moved the hosted-beta restrictions and production boundary to the top of the page.
• Added current-status, capabilities, repository-map, governance, release, security, and attribution sections.
• Updated the documented toolchain to Node.js >=22.13.0 <25 and npm 11.9.0.
• Replaced remaining product-facing Mike terminology while preserving upstream attribution.
• Expanded verification documentation to reflect the repository's actual deterministic and fail-closed checks.

Why

The previous front page functioned mainly as a setup guide and contained stale toolchain requirements. It did not prominently identify the public beta or explain the repository's current governance, verification, and restricted-use boundaries.

Impact

This is a documentation-only change. It does not alter application code, workflows, release controls, or security boundaries.

Validation

The content was checked against the current README.md, root package.json, config/ross-brand.json, and the repository's documented release and exact-head verification model. Exact-head Baseline verification remains required before merge.