Route visual compares to the WordPress origin

[chubes4]

Summary

• use the direct local WordPress Playground origin for internal visual comparison captures
• retain the preview proxy for exposed/public preview modes
• align visual comparison with the internal-origin boundary established for editor commands in Fix editor saves on internal Playground origin #2102

Closes #2109.

Verification

• npm run build
• npx tsx tests/browser-visual-compare-contract.test.ts
• npx tsx tests/browser-callback-materialization-contracts.test.ts
• real eight-route 27-university-department visual comparison

Before this change, proxy-port candidate routes failed with ERR_TOO_MANY_REDIRECTS. After the change, all eight source and candidate captures complete on the direct WordPress origin and produce full screenshots, DOM snapshots, and pixel metrics. The same run validates 269/269 Gutenberg blocks.

Compatibility

No command or artifact schema changes. Explicit public/routed preview modes still resolve through their requested origins; only the default local internal capture base changes when wordpressUrl is available.

AI assistance

• Model: OpenAI GPT-5.6 Sol
• Tool: OpenCode
• Used for: cross-stack reproduction, implementation, tests, and university runtime verification with Chris Huber.