feat: GitHub-link op DONE-card + pushed_at doorvoer

- lib/job-status-url.ts: getBranchUrl(repoUrl, branch) → GitHub tree URL
- JobState + ClaudeJobEvent: pushed_at? veld toegevoegd
- realtime/solo/route.ts: pushed_at in Prisma-select, JobPayload en mapping
- SoloBoardProps + TaskDetailDialog: repoUrl prop doorgevoerd
- task-detail-dialog: "Open op GitHub"-link als done + pushed_at + branch + repoUrl
- 3 unit-tests voor getBranchUrl; totaal 261 tests groen

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/job-status-url.ts

@@ -0,0 +1,4 @@
+export function getBranchUrl(repoUrl: string, branch: string): string {
+  const base = repoUrl.replace(/\.git$/, '').replace(/\/$/, '')
+  return `${base}/tree/${branch}`
+}