The runs list shows agent runs, checks and deploys together by default, with the three as filters #2381

Part of #1124. Both tries changed everything at once and went red in test/web-origins.test.ts and test/web-code.test.ts.

Done looks like:

• [ ] /:owner/:name/runs lists agent runs, checks and deploys newest first, with three filter links. A check's row names the pull, the head, the state and how long it took.
• [ ] No change to the shared layout, the nav or any other page.
• [ ] Test: a check and an agent run both show with no filter, and each filter narrows the list.
• [ ] Run test/web-origins.test.ts and test/web-code.test.ts with your test and quote the result.