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/web/handler.go

@@ -47,6 +47,7 @@ func NewHandler() http.Handler {
 		if ld.ns != "" {
 			a.NS = "Tailscale mesh · " + ld.ns
 		}
+		a.Timeline = ld.timeline
 		if ld.run != nil {
 			nodes := atlas.RunNodes(*ld.run)
 			for i := range a.Stages {
@@ -71,10 +72,11 @@ func NewHandler() http.Handler {
 
 // liveOverlay holds cluster-sourced substrate facts (node specs + namespace line).
 type liveOverlayData struct {
-	hosts  []atlas.Host
-	ns     string
-	run    *atlas.RunSummary
-	deploy *atlas.Deploy
+	hosts    []atlas.Host
+	ns       string
+	run      *atlas.RunSummary
+	deploy   *atlas.Deploy
+	timeline []atlas.RunDot
 }
 
 // live cache: query the cluster at most once per TTL; fall back to the authored
@@ -110,6 +112,9 @@ func liveOverlay() liveOverlayData {
 		if r, err := atlas.LatestRunJobs(raw); err == nil {
 			d.run = &r
 		}
+		if dots, err := atlas.RecentRuns(raw, 12); err == nil {
+			d.timeline = dots
+		}
 	}
 	if raw, err := cluster.Deployment(); err == nil {
 		if dep, err := atlas.DeployState(raw); err == nil {