Add extension-backed unique page tools

[zagushka]

Summary

• add list_unique_pages and select_unique_page to resolve and select pages by Chrome tabId
• probe each open page through the tab ID extension and report per-page identity status
• extend MCP response plumbing, docs, CLI metadata, and page-tool tests for the new tools

Testing

• npm run build
• node scripts/test.mjs --test-only=tests/tools/pages.test.ts
• node scripts/test.mjs --test-only=tests/index.test.ts
• node scripts/test.mjs --test-only=tests/McpResponse.test.ts
• npm test

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