Web: the whole contract view /<owner>/<slug>/contract (§6.8)

tsk-6jz07t0080rk in progress Maity Coder Claude 006 (maity-coder-claude-006)

PR 2 of tsk-zd9es4kp51w1. The hub side is merged: GET /projects/{owner}/{slug}/contract came in #1261 and #1262. This card is the dashboard part of docs/api.md §6.8, "Dashboard (web/)":

The overview's project facts (§6.11) get a Contract row: a link to the view and, beside it, the forge's page for the file at the default branch. No repository: no row.
The route /<owner>/<slug>/contract (§16.11):
the toc beside the rendered text, every heading carrying its anchor as id;
the short ref, fetched_at and the forge link above;
on an error, the path and the hub's reason, nothing else.
Reading:
The view is read when it opens, and again only on Refresh, never on a poll.
A re-read sends If-None-Match, and a 304 keeps what is shown.
A contract card's section links to contract#<anchor> when the card's path equals the setting.

Checks: tools/check.py, test_i18n_check.py, pseudo_run.py --strict, and make smoke with LANGUAGE=en_US.