docs: align README with MeshView and this fork

[dborup]

The README pointed readers at upstream badges, images and live services, and included outdated architecture and testing claims. It now introduces CoreScope for MeshView, links MeshView and this fork's CI, and documents building and running this repository locally.

The update also corrects configuration and test instructions, retains upstream attribution, and labels inherited screenshots as upstream examples. Only README.md changes.

Validation:

• git diff --check passed.
• All 12 local file references exist; all 9 public URLs returned HTTP 200.
• The JSON example parses and all 6 shell blocks pass bash -n.
• Rendered the Markdown in Chromium at desktop and mobile widths; all images loaded and mobile had no horizontal page overflow.
• Docker build was not run because the local Docker daemon is stopped. Application test suites were not rerun for this documentation-only change; CI will run the repository checks.