[evdatsion]

What this does

Refreshes the root README and docs to reflect the completed six-phase build and give the project a modern look.

• New visuals in docs/: a hero banner (hero.svg), a system-at-a-glance diagram (overview.svg: open-core engine, the moat, and the control plane), and a terminal demo of the daily loop (demo.svg). They are self-contained dark SVG cards, so they read the same on GitHub light and dark.
• Rewritten README: centered hero, a refreshed badge row, a short "Why Cohort", the how-it-works loop, the demo, the "what's inside" diagram, the six MCP tools and the CLI commands as tables, a collapsible quickstart, and a roadmap that marks all six phases shipped. The stale "cohort-mcp (Phase 1, in progress)" framing is removed.
• The existing architecture diagram is now client-neutral: it no longer names a single client.
• CHANGELOG.md records Phases 2 through 6 and this refresh under Unreleased.

Docs-only change. No code, tool, or behavior changes.

Verification

• All 18 local link and image targets in the README resolve; the four SVGs are well-formed XML.
• No em or en dashes in the README, CHANGELOG, the SVGs, or the other docs authored recently (project style).
• The tool and CLI tables match what actually ships; the install instructions stay pinned to the real v0.3.0 release; the control plane is described as separate and optional.
• Local redaction scan (gitleaks) clean.