fix(bench): gate seeding on repo+index readiness and match read counts semantically

Two benchmark-harness races were being scored as agent failures. A freshly
seeded throwaway repo could 404 for an independent reader (the agent, a fresh
process) before Gitea made it consistent, and the async issue indexer lagged so
`search issues`/`search prs` returned nothing right after seeding — leaving the
agent unable to find the target it was asked to act on.

seedRepo now blocks until an independent read confirms the repo is reachable,
its full seeded issue and pull spread is visible, and a seeded issue and pull
are returned by the search index, before releasing the agent. It polls up to
60s and throws a loud harness error on timeout rather than letting a
propagation delay become a scored agent failure.

Also add an optional `pattern` regex to RequiredFact so a read answer's count is
recognised semantically rather than as a fixed phrase: "5 issues are currently
open" no longer fails against the literal "5 issues are open", while the
alphabetic-only filler run keeps a wrong count beside the right number (e.g.
"5 issues ... 3 open") failing.

bench/task-suite.ts

@@ -92,6 +92,11 @@ function readTasks(): BenchTask[] {
         {
           description: "the repository has 5 open issues",
           anyOf: ["5 open", "five open", "open issues: 5", "open: 5", "5 issues are open"],
+          // "5" followed by "open" across up to four alphabetic filler words, so
+          // natural padding ("5 issues are currently open") is recognised while a
+          // digit between them (a wrong "5 issues, 3 open") is not: the filler run
+          // is alphabetic only, so it cannot span another count.
+          pattern: "\\b5(?: [a-z]+){0,4} open\\b",
         },
       ]),
     },