Be better about providing a bike-on-train option

[graue]

Here is a route from the Mission to the Ferry Building that is perfect for BART, but instead BikeHopper suggests transferring from BART to the 2 bus for 3 blocks:

link

The zero-transfer option is bike on bus and is slower than biking the whole way.

Thoughts:

• Be less aggressive in avoiding bad bike infra for short lengths (Be less silly about avoiding bad bike infra for very short lengths #96, see also Weird routing in the Mission to a farther bus stop #105)
• Maybe just hardcode always having a bike-on-train option in the results if it's reasonable. It's weird that bike on 14R would kick bike on BART out of the results