feat(atlas): Phase C — recent-runs timeline

A strip of the last 12 runs (aggregate pass/fail/running per run) below the
substrate ribbon, coloured, newest-first, run # on hover. Parsed from the same
Gitea /actions/tasks fetch (RecentRuns, test-first; State refactored to share
the aggregate). No new RBAC. Hidden when no live data.

Verified: build/vet/lint(0)/test green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/gitea/client.go

@@ -21,7 +21,7 @@ func base() string {
 
 // Runs returns the raw /actions/tasks JSON for mathias/cad-atlas (newest first).
 func Runs() ([]byte, error) {
-	url := base() + "/api/v1/repos/mathias/cad-atlas/actions/tasks?limit=20"
+	url := base() + "/api/v1/repos/mathias/cad-atlas/actions/tasks?limit=50"
 	client := &http.Client{Timeout: 5 * time.Second}
 	resp, err := client.Get(url) //nolint:noctx // short-lived, timeout on the client
 	if err != nil {