Simplify dashboard and redesign README

[chai1any]

What changed

• removes marketing headlines, vague helper prose, the privacy billboard, and verbose empty states from the dashboard
• reduces every tool view to a compact functional title and its controls
• shortens first-run pairing to two concrete steps
• redesigns the README around the existing SVG logo, fast installation, capability mapping, measured proof, and task-oriented documentation

Why

The dashboard read like a landing page instead of an operational tool, and the README buried its strongest value and evidence in long prose.

Validation

• 8 Chromium dashboard tests, including mobile and WCAG audits
• live authenticated browser evidence-to-memory workflow
• documentation link and heading checks
• release build
• 12/12 search-quality queries at rank one with no fixture leakage