feat(master): htmx UI with live service overview and agent management

Vendored static assets (sha256):
e209dda5c8235479f3166defc7750e1dbcd5a5c1808b7792fc2e6733768fb447  htmx.min.js (htmx.org@2.0.4)
83eca6fa0611fe2b0bf1700b424b88b5eced38ef448ef9760a2ea08fbc875611  htmx-ext-sse.js (htmx-ext-sse@2.2.2)

internal/master/web/views.go

@@ -0,0 +1,51 @@
+package web
+
+import (
+	"strings"
+
+	"github.com/shcizo/package-updater/internal/imageref"
+	"github.com/shcizo/package-updater/internal/master/model"
+	"github.com/shcizo/package-updater/internal/protocol"
+)
+
+type serviceGroup struct {
+	Title    string
+	Services []model.Service
+}
+
+// groupServices groups machine-bound services per agent and Swarm services
+// in one group, keeping the store's order (machines first, Swarm last).
+func groupServices(services []model.Service) []serviceGroup {
+	var groups []serviceGroup
+	index := map[string]int{}
+	for _, s := range services {
+		title := s.AgentName
+		if s.Kind == protocol.KindSwarm {
+			title = "Swarm"
+		} else if title == "" {
+			title = "Unknown agent"
+		}
+		i, ok := index[title]
+		if !ok {
+			i = len(groups)
+			index[title] = i
+			groups = append(groups, serviceGroup{Title: title})
+		}
+		groups[i].Services = append(groups[i].Services, s)
+	}
+	return groups
+}
+
+// shortRef shortens a digest in an image reference to 12 hex characters.
+func shortRef(ref string) string {
+	r := imageref.Parse(ref)
+	if hex, ok := strings.CutPrefix(r.Digest, "sha256:"); ok && len(hex) > 12 {
+		r.Digest = "sha256:" + hex[:12] + "…"
+	}
+	return r.String()
+}
+
+type agentRow struct {
+	model.Agent
+	Online bool
+}