docs: give theme-toggle its Sign

[rqbazan]

Summary

theme-toggle gets its Sign, and its README opens with the Sign, the name and the Tagline.

+brand/                  # sign.svg, sign-readme.svg, README.md
 README.md               # header: Sign, "theme-toggle", Tagline
 package.json            # author: rcrd <ricardo@variable.land>
+.changeset/             # patch

-# @variablelab/theme-toggle
+<Sign>
+<h1>theme-toggle</h1>
+The theme is set before first paint.

The README links sign-readme.svg by its absolute raw.githubusercontent.com/.../HEAD/... URL, so on this branch's file view the image is broken until merge. brand/ stays out of the npm tarball; npm loads the image from that URL.

Evidence

• Before: the package as the title; author rcrd <rcrd@variable.land>.
  After: the header above, rendered with the image pointed at this branch, checked light and dark. The Sign passes the covered-names test at 16px.
• pnpm rr check passes. pnpm changeset status: @variablelab/theme-toggle 2.0.1, patch.

Merge Danger

Door: two-way

Docs, two SVGs and the author field.

Blast Radius: README

Merging opens the "chore: update versions" PR; merging that one publishes 2.0.1, and npm shows the new README.

🤖 Generated with Claude Code

https://claude.ai/code/session_01CA1WV2T1uj44yHQH6LHLyN

[changeset-bot]

🦋 Changeset detected

Latest commit: e7f3226

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@variablelab/theme-toggle	Patch

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