Make the HTTP timeout configurable

[TheCoder30ec4]

Motivation

request_json uses a fixed 60 s timeout. Latency-sensitive agents may want 5 to 10 s and then fall back, while batch jobs may want more.

Proposal

Add Router(..., timeout=60), stored on the router and passed to jev.choose_via_* and on to request_json(timeout=...).

Done when

• The timeout reaches urlopen (assert with a mock)
• Documented in the README API table