feat: auto-link phrases in the resolve answer (tracer)

- golem15_seo_autolinks (migration 202610280007) and the settings column
  autolink_max (Links tab, 0 to 20, default 3)
- classes/autolinks.go: checked save and delete with history, ForPage
- ok resolve answers carry autolinks for the page's locale without
  disabled phrases and links to the page itself, and autolink_max

models/autolink.go

@@ -0,0 +1,113 @@
+package models
+
+import (
+	"strconv"
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// The origins of an auto-link phrase: entered in the admin, added from a
+// record's focus keyphrase, or created through MCP.
+const (
+	AutolinkOriginManual    = "manual"
+	AutolinkOriginKeyphrase = "keyphrase"
+	AutolinkOriginMCP       = "mcp"
+)
+
+// AutolinkOrigins lists the origins in filter order.
+var AutolinkOrigins = []string{AutolinkOriginManual, AutolinkOriginKeyphrase, AutolinkOriginMCP}
+
+// The limits of an auto-link phrase and of the settings' autolink_max
+// (UI-SPEC C20, C22).
+const (
+	MinAutolinkPhrase  = 3
+	MaxAutolinkPhrase  = 200
+	MaxAutolinkURL     = 2048
+	DefaultAutolinkMax = 3
+	MinAutolinkMax     = 0
+	MaxAutolinkMax     = 20
+)
+
+// Autolink is one phrase of the auto-link table on golem15_seo_autolinks
+// (D-82, P33-45): texts link the phrase's first occurrence to URL (a path
+// or an absolute http(s) address). Locale is the content locale it applies
+// in, "" for every locale; a disabled phrase is kept but never linked.
+type Autolink struct {
+	ID        uint       `gorm:"column:id;primaryKey"`
+	Phrase    string     `gorm:"column:phrase"`
+	URL       string     `gorm:"column:url"`
+	Locale    string     `gorm:"column:locale"`
+	Enabled   bool       `gorm:"column:enabled"`
+	Origin    string     `gorm:"column:origin"`
+	Note      string     `gorm:"column:note"`
+	CreatedAt *time.Time `gorm:"column:created_at"`
+	UpdatedAt *time.Time `gorm:"column:updated_at"`
+}
+
+func (Autolink) TableName() string { return "golem15_seo_autolinks" }
+
+// MorphName names an auto-link in history and the admin.
+func (Autolink) MorphName() string { return `Golem15\SEO\Models\Autolink` }
+
+// Fillable lists the form's columns.
+func (*Autolink) Fillable() []string {
+	return []string{"phrase", "url", "locale", "enabled", "note"}
+}
+
+// Rules is empty: the Auto-links controller and the service check a
+// phrase before a save (classes.AutolinkProblems).
+func (*Autolink) Rules() map[string]string { return map[string]string{} }
+
+// NewAutolink is a phrase with the form's defaults: every locale, active,
+// entered by hand.
+func NewAutolink() Autolink {
+	return Autolink{Enabled: true, Origin: AutolinkOriginManual}
+}
+
+// IDText is the auto-link's id as text.
+func (a Autolink) IDText() string { return strconv.FormatUint(uint64(a.ID), 10) }
+
+// The filter scopes of the Auto-links list (UI-SPEC C22).
+const (
+	FilterAutolinkLocale = "FilterAutolinkLocale"
+	FilterAutolinkOrigin = "FilterAutolinkOrigin"
+	// AutolinkLocaleAll is the locale filter's value of the phrases that
+	// apply in every locale.
+	AutolinkLocaleAll = "all"
+)
+
+// FilterScopes lists the Auto-links list's filter scopes.
+func (Autolink) FilterScopes() []string {
+	return []string{FilterAutolinkLocale, FilterAutolinkOrigin}
+}
+
+// FilterScope narrows the Auto-links list by locale ("all" for the
+// phrases of every locale) or origin; an unknown origin matches nothing.
+// The active filter is a switch on the enabled column.
+func (Autolink) FilterScope(name string, db *gorm.DB, value any) *gorm.DB {
+	if db == nil {
+		return db
+	}
+	switch name {
+	case FilterAutolinkLocale:
+		s, _ := value.(string)
+		if s == AutolinkLocaleAll {
+			s = ""
+		}
+		return db.Where("golem15_seo_autolinks.locale = ?", s)
+	case FilterAutolinkOrigin:
+		s, _ := value.(string)
+		for _, o := range AutolinkOrigins {
+			if o == s {
+				return db.Where("golem15_seo_autolinks.origin = ?", s)
+			}
+		}
+		return db.Where("1 = 0")
+	}
+	return db
+}
+
+func init() {
+	Register(Autolink{})
+}