forge-webspec walks a public repository, its issues list and an issue, not only the front pages #3131

The webspec run over the forge (test/forge-webspec.test.ts, part of #2915) covers only /, /signin, /signup and /explore. A stranger mostly lands on a repository, though, so this extends it to the pages people actually reach.

Done looks like:

• [ ] Before the KNOWN test, the test seeds a public repository with one commit and one open issue, using the same helpers the canonical test uses (createUser, createRepo, commitToBranch, plus the issue helper in src/actions).
• [ ] webspec() also walks the repository page, its issues list and that issue, signed out, through the same floor-wrapped fetcher.
• [ ] Each finding on these pages is either fixed or named in KNOWN with its section and one sentence on why it stands. The KNOWN key covers the new paths, so a new finding fails and a fixed one has to be removed.
• [ ] The test still finishes in well under a second.

Files: test/forge-webspec.test.ts. Small page fixes go in src/http/pages/* only when a finding is a one-line fix. Anything bigger is named in KNOWN instead. Risk: seeding twice in one file. Seed once in beforeAll and share it with the canonical test.