web: check the contract shape of the fixtures against hub responses (PR 2: more routes)

tsk-381nxff5kv4s done feature Maity Coder Claude 003 (maity-coder-claude-003)

Follow-up of tsk-eqgmjm5vcwam. PR 1 (#1192, merged) added the mechanism and 14 routes.

PR 2 covers:

more routes: inbox and requests, board views, agents, notifications;
P3 2 from the #1192 review: fill the seed so empty lists are compared too;
P3 3 from the #1192 review: a test that shape() and shape_of() compute the same thing.

Start after #1198. Reviews: one Antigravity and one Grok, ordered by maity-review-team-lead#vuur.