Link views from the zone list, add breadcrumbs and view colours

The view shown in the zone list and on the zone page now links to that
view. The zone page and changeset page get breadcrumbs, and the zone list
keeps its filters in the address so going back restores them. Views can
be given a colour (Views > Edit, `jarl view color`, PUT /views/{id}/color)
so zones of the same view are easy to spot; the colour is UI-only, kept
outside changesets, and needs no deploy.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/server/h_config.go

@@ -3,6 +3,7 @@ package server
 import (
 	"encoding/json"
 	"net/http"
+	"slices"
 	"sort"
 	"strconv"
 	"strings"
@@ -46,10 +47,14 @@ func (s *Server) listViews(w http.ResponseWriter, r *http.Request, p *auth.Princ
 	if err != nil {
 		return err
 	}
+	colors, err := s.store.ViewColors(r.Context())
+	if err != nil {
+		return err
+	}
 	out := []api.View{}
 	for _, v := range st.OrderedViews() {
 		if p.Can(auth.Action{Resource: auth.ResViews, View: v.Name}) {
-			out = append(out, presentView(st, v))
+			out = append(out, presentView(st, v, colors))
 		}
 	}
 	writeJSON(w, http.StatusOK, out)
@@ -79,14 +84,58 @@ func (s *Server) getView(w http.ResponseWriter, r *http.Request, p *auth.Princip
 	if err != nil {
 		return err
 	}
-	writeJSON(w, http.StatusOK, presentView(st, v))
+	colors, err := s.store.ViewColors(r.Context())
+	if err != nil {
+		return err
+	}
+	writeJSON(w, http.StatusOK, presentView(st, v, colors))
 	return nil
 }
 
-func viewObject(st *model.State, id int64) any {
-	if v := st.Views[id]; v != nil {
-		return presentView(st, v)
+func (s *Server) viewObject(r *http.Request) func(st *model.State, id int64) any {
+	return func(st *model.State, id int64) any {
+		if v := st.Views[id]; v != nil {
+			colors, _ := s.store.ViewColors(r.Context())
+			return presentView(st, v, colors)
+		}
+		return nil
 	}
+}
+
+// setViewColor sets the colour the web UI shows a view in. It is not part
+// of the configuration, so it applies at once, outside changesets.
+func (s *Server) setViewColor(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
+	st, err := s.state(r)
+	if err != nil {
+		return err
+	}
+	v, err := s.viewByPath(r, st, p)
+	if err != nil {
+		return err
+	}
+	if err := require(p, auth.Action{Resource: auth.ResViews, Write: true, View: v.Name}); err != nil {
+		return err
+	}
+	var in api.ViewColor
+	if err := decodeJSON(r, &in); err != nil {
+		return err
+	}
+	if in.Color != "" && !slices.Contains(model.ViewColors, in.Color) {
+		return badRequest("unknown colour %q: use one of %s, or \"\" for the default", in.Color, strings.Join(model.ViewColors, ", "))
+	}
+	if err := s.store.SetViewColor(r.Context(), v.ID, in.Color); err != nil {
+		return err
+	}
+	detail := in.Color
+	if detail == "" {
+		detail = "default"
+	}
+	s.eng.Audit(r.Context(), p, "view.color", "view", v.ID, v.Name, "success", detail)
+	colors, err := s.store.ViewColors(r.Context())
+	if err != nil {
+		return err
+	}
+	writeJSON(w, http.StatusOK, presentView(st, v, colors))
 	return nil
 }
 
@@ -95,7 +144,7 @@ func (s *Server) createView(w http.ResponseWriter, r *http.Request, p *auth.Prin
 	if err != nil {
 		return err
 	}
-	return s.mutate(w, r, p, "", []engine.Request{request(engine.OpViewCreate, 0, body)}, viewObject)
+	return s.mutate(w, r, p, "", []engine.Request{request(engine.OpViewCreate, 0, body)}, s.viewObject(r))
 }
 
 func (s *Server) updateView(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
@@ -112,7 +161,7 @@ func (s *Server) updateView(w http.ResponseWriter, r *http.Request, p *auth.Prin
 		return err
 	}
 	id := v.ID
-	return s.mutate(w, r, p, "", []engine.Request{request(engine.OpViewUpdate, id, body)}, func(st *model.State, _ int64) any { return viewObject(st, id) })
+	return s.mutate(w, r, p, "", []engine.Request{request(engine.OpViewUpdate, id, body)}, func(st *model.State, _ int64) any { return s.viewObject(r)(st, id) })
 }
 
 func (s *Server) deleteView(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {