feat: management API and an MCP tool per SEO admin operation

- /_seo/api/v1 routes for the effective SEO of a URL with sources and
  owner, URL rules, redirects (loops refused with redirect_loop), the
  404 log actions, robots.txt and its tester, settings and history
- the CMS-data issue report: missing and duplicate titles and
  descriptions, rules over records, redirect chains, canonicals to
  noindex or redirected addresses, noindex addresses robots.txt blocks
- 24 MCP tools on those routes (backend guard, golem15.seo.manage)
- AdminOperations maps every admin operation to its tool;
  TestEveryAdminOperationHasTool and TestMCPReadToolsAreGET guard drift
- robots.txt writes go through classes.SaveRobots from the admin too

controllers/api/seo.go

@@ -3,6 +3,7 @@ package api
 import (
 	"context"
 	"net/http"
+	"strings"
 
 	"git.golem15.com/golem15/sm-seo-plugin/classes"
 	"gorm.io/gorm"
@@ -69,3 +70,67 @@ func SetSEO(service func() *classes.Service) http.HandlerFunc {
 		return http.StatusOK, res, nil
 	})
 }
+
+// GetSEOInput is the query of GET /_seo/api/v1/seo.
+type GetSEOInput struct {
+	URL string `json:"url" query:"url" jsonschema:"the page: a path such as /blog/post or an absolute URL of the site"`
+}
+
+// GetSEO serves GET /_seo/api/v1/seo?url= (D-13): the effective SEO of a
+// URL with the source of every value (rule, record, template, global,
+// content or default), the redirect decision (action redirect or gone with
+// the location), the owner a change would be written to, and the P1
+// warnings (a URL rule overriding the record, a canonical that redirects
+// or points to a noindex page). 422 for a URL that is not a path or
+// http(s) URL.
+func GetSEO(service func() *classes.Service) http.HandlerFunc {
+	return manage(service, func(ctx context.Context, svc *classes.Service, r *http.Request) (int, any, error) {
+		target := r.URL.Query().Get("url")
+		res, err := svc.Resolver().Resolve(ctx, target)
+		if err != nil {
+			return 0, nil, err
+		}
+		db, err := read(ctx, svc)
+		if err != nil {
+			return 0, nil, err
+		}
+		owner, _, err := svc.FindOwner(ctx, db, target, false)
+		if err != nil {
+			return 0, nil, err
+		}
+		var status classes.StatusView
+		switch {
+		case owner.WrittenTo == classes.WrittenToRecord:
+			if status, err = svc.RecordStatus(ctx, owner.Type, owner.ID); err != nil {
+				return 0, nil, err
+			}
+		case owner.RuleID != 0:
+			rule, err := classes.LoadRule(db, owner.RuleID)
+			if err != nil {
+				return 0, nil, err
+			}
+			status = svc.RuleStatus(ctx, rule)
+		}
+		warnings := []string{}
+		for _, c := range status.Callouts {
+			text := strings.TrimSpace(c.Title + " " + c.Text)
+			warnings = append(warnings, text)
+		}
+		sources := res.Sources
+		if sources == nil {
+			sources = map[string]string{}
+		}
+		return http.StatusOK, map[string]any{
+			"url":      res.URL,
+			"action":   res.Action,
+			"status":   res.Status,
+			"location": res.Location,
+			"locale":   res.Locale,
+			"staging":  res.Staging,
+			"seo":      res.SEO,
+			"sources":  sources,
+			"owner":    owner,
+			"warnings": warnings,
+		}, nil
+	})
+}