forge-webspec walks the admin pages too: /audit, /backups, /fleet/graph, /crew, a repo's tree, blob and commit #3206

test/forge-webspec.test.ts walks the signed-out pages and six signed-in ones (#3173). The admin pages and code browsing are not walked yet.

Done looks like:

• [ ] SIGNED_IN adds /audit, /backups, /fleet/graph and /crew. PATHS adds a fixture repository's tree, a blob and a commit.
• [ ] Each finding is either fixed in the page, or named in KNOWN or KNOWN_SIGNED_IN with its section and why, as the file already does.
• [ ] The file stays under the test budget (1 s per test, 10 s per file).

Files: test/forge-webspec.test.ts, and the pages whose findings get fixed.