Log failed API requests, and default to HTTP/1.1

[shellicar]

Summary

• A failed API request now logs its cause chain, how the transport classified it, and every retry with its attempt number and delay.
• An error in the log keeps its name, message, stack and cause instead of rendering as an empty object.
• New http.allowH2 setting, off by default, so requests negotiate HTTP/1.1 and an over-limit request fails immediately with a readable 413.
• Each connection logs the HTTP protocol it negotiated.
• @types/node moves to 26 across the workspace, matching the Node version CI builds the binary with.