Make the tldraw.com top-left logo link to tldraw.dev

Problem

On tldraw.com, the tldraw logo in the editor's top-left panel currently links to / (the app home). It would be more useful as a link to tldraw.dev so visitors can discover the SDK and docs from the canvas, hardening the symbiosis between the two sites.

Proposed behavior

• Clicking the top-left tldraw logo on tldraw.com opens https://tldraw.dev in a new tab.
• Use target="_blank" with rel="noopener noreferrer" since this navigates off-app.

Scope

Only the top-left logo on tldraw.com (the editor top-left panel). Other logos (docs site header/footer, examples app header, sidebar/dialog decorative logos) are not in scope for this issue.

Affected code

• apps/dotcom/client/src/tla/components/TlaEditor/TlaEditorTopLeftPanel.tsx — currently <Link to="/"> wrapping <TlaLogo />.

Considerations

• The current link is the only in-app affordance to get back to the file index when viewing a file. If we repoint the logo to tldraw.dev, we should confirm there is still an obvious path back to the home/file index (e.g. via the sidebar). If not, that navigation needs to move somewhere visible before this change ships.
• This change applies to all three render contexts of the top-left panel: signed-out root, anonymous guest, and published-file viewer.