Allow changing the landing page title via config

[pgporada]

When I have many sunlight logs open in my browser, it's difficult to tell where I am at a glance. What are the odds that anyone actually needs this? Slim to none, but it would help me.

Adds a new name config option to allow changing the landing page's page title. If unset, it'll default to Sunlight like all currently running logs have.

Example config:

$ cat config.yaml 
name: "Phil Log"
listen:
  - ":8080"

checkpoints: checkpoints.db

logs:
  - shortname: testlog
    submissionprefix: "https://localhost:8080/testlog"
    monitoringprefix: "https://localhost:8080/testlog"
    inception: "2026-05-22"
    notafterstart: "2026-01-01T00:00:00Z"
    notafterlimit: "2027-01-01T00:00:00Z"
    secret: seed.bin
    cache: cache.db
    localdirectory: ./data/testlog