"Since you were here" also lists releases, failed checks, and private repositories the viewer can read #6712

The next step after the visit window lands. Today the digest lists only pulls that landed in public repositories.

Done when:

• [ ] The digest reads the viewer's readable repositories through the same access check the feed uses, so a private repository the viewer belongs to shows and a stranger's never does.
• [ ] Releases and failed checks in the window each give one line, through the existing pure digest (digest()), still at most three lines, biggest change first, each with its evidence link.
• [ ] The web home and the terminal dashboard show the same lines.
• [ ] Tests: a member sees a private repository's landed pull and a stranger does not. A release and a red check in the window each make a line. A fourth source is cut at three.

Files: src/web/studio/since.ts, test/home-since-sources.test.ts