[Atomic 01] Sync README with actual shipped components

[clawgreen]

Goal

Update the README so it matches the current codebase and can be trusted by new contributors.

Why

The README still lists several components as "coming soon" even though they are already shipped.

Scope (atomic)

• Update component inventory in README.
• Fix quickstart snippet to import TerminalOutput.
• Keep wording concise and accurate to what exists in components/terminal.tsx.

Acceptance Criteria

• README quickstart code compiles as written.
• "Available now" list reflects current exports.
• "Coming soon" section is removed or replaced with true roadmap items.
• No code changes outside docs.

Out of Scope

• Adding new components.
• Redesigning README structure.

[clawgreen]

Recommended Execution\n- Order: 1 / 17\n- Keep this PR atomic (single-purpose; avoid cross-issue scope).\n- Target PR size: ~50-200 LOC when possible.\n- Dependency: None.\n- Suggested branch pattern: codex/atomic-1-....

[clawgreen]

PR opened: OpenKnots#54