[Bug]: [MCP/CLI] Bare loopback IP addresses (127.0.0.1:port) and hosts with ports reported to fail to navigate; reporter attributes this to scheme inference

Finding: In Playwright CLI/MCP (playwright open, tab-new, browser_navigate), a reporter says schemeless 127.0.0.1:3000 fails with net::ERR_SSL_PROTOCOL_ERROR and bare example.com:8080 fails with net::ERR_ABORTED [https://github.com/microsoft/playwright/issues/43263]. The issue states no Playwright version; it was filed 2026-10-10 and the affected release is unknown. Reported symptoms: The issue shows 'page.goto: net::ERR_SSL_PROTOCOL_ERROR at https://127.0.0.1:3000/'. The exact error text is shown only for the 127.0.0.1:3000 example; the reporter says other loopback addresses such as 0.0.0.0 and [::1] fail similarly, without shown output. For a bare host with a port, the issue shows 'page.goto: net::ERR_ABORTED at example.com:8080' [https://github.com/microsoft/playwright/issues/43263]. Reporter's proposed cause (hypothesis; not maintainer-confirmed; not verified against the repository here): The reporter supplies a snippet they describe as checkUrlAndNavigate in packages/playwright-core/src/tools/backend/tab.ts. In that reporter-supplied snippet, new URL(url) is tried and, on a throw, http:// is prepended only when the string starts with localhost, otherwise https://. The reporter says numeric loopback IPs make new URL() throw and so get https://, and that host:port inputs beginning with a letter parse as a scheme under WHATWG rules, so no http/https scheme is added [https://github.com/microsoft/playwright/issues/43263]. Reporter's requested behavior: schemeless URLs should be normalized; loopback addresses (localhost, 127.0.0.1, 0.0.0.0, [::1]) should default to http://, other bare hosts (e.g. example.com:8080, playwright.dev) to https:// [https://github.com/microsoft/playwright/issues/43263]. Workaround: No workaround is stated or tested in the source. Status: The supplied data shows the issue open with zero thread comments (coverage is head/tail only), and no maintainer response, linked fix commit or released fix. The issue embeds screenshots, one labeled as fixed behavior; they were not inspected. Limitation: Single external report; no KFA reproduction or code inspection.