docs(org): refocus README on AI agent control plane + coverage framing

[haasonsaas]

What

Replaces the org front-door tagline, which still led with the eval-era line:

The organizational operating system for AI agent workforces — evaluation, governance, and observability for shipping accountable AI.

with the visibility + governance + coverage frame now shipped across hopper (#192–197):

The control plane for AI agent workforces — see which agents, assistants, and tools are running, govern what each one is allowed to do through policy, approvals, evaluation, cost, and audit, and measure how much of their real action surface is actually covered. Widen autonomy only as the record supports it.

Why

The .github README is the first surface a technical buyer or investor hits on github.com/evalops, and it was the one positioning surface the hopper copy-guardrail (#197) doesn't watch — so it kept the old framing while the site moved. Leads with coverage (how much of what agents can do is governed), not census.

Follow-ups (not in this PR)

• Extend the positioning-frame copy guardrail to the .github repo so this surface can't drift again.
• Key Repos table still points at deprecated repos (proto, service-runtime, console are all archived/absorbed into platform).

🤖 Generated with Claude Code

[cursor]

PR Summary

Low Risk
Documentation-only change to org README copy; no runtime, auth, or data paths affected.

Overview
Updates the org profile README tagline so GitHub’s front door matches hopper’s current positioning.

It swaps the eval-era line (“organizational operating system… evaluation, governance, and observability”) for the control plane framing: visibility into running agents/assistants/tools, governance via policy/approvals/evaluation/cost/audit, action-surface coverage measurement, and widening autonomy only when the record supports it.

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