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

updates/202610280007_create_golem15_seo_autolinks.go

@@ -0,0 +1,47 @@
+package updates
+
+import (
+	"github.com/go-gormigrate/gormigrate/v2"
+	"gorm.io/gorm"
+)
+
+// createAutolinks creates golem15_seo_autolinks, the auto-link phrases
+// (D-82, P33-45): a phrase, the address it links to, its locale (empty for
+// every locale), whether it is active, where it came from (manual,
+// keyphrase or mcp) and a note, one row per phrase (any letter case) and
+// locale. The settings get autolink_max, the phrases linked in one text
+// at most (3 by default, 0 turns auto-linking off).
+var createAutolinks = []*gormigrate.Migration{
+	{
+		ID: "202610280007_create_golem15_seo_autolinks",
+		Migrate: func(tx *gorm.DB) error {
+			if err := tx.Exec(`CREATE TABLE golem15_seo_autolinks (
+	id BIGSERIAL PRIMARY KEY,
+	phrase TEXT NOT NULL,
+	url TEXT NOT NULL,
+	locale TEXT NOT NULL DEFAULT '',
+	enabled BOOLEAN NOT NULL DEFAULT TRUE,
+	origin TEXT NOT NULL DEFAULT 'manual',
+	note TEXT NOT NULL DEFAULT '',
+	created_at TIMESTAMP(0) NULL,
+	updated_at TIMESTAMP(0) NULL
+)`).Error; err != nil {
+				return err
+			}
+			if err := tx.Exec(`CREATE UNIQUE INDEX golem15_seo_autolinks_phrase ON golem15_seo_autolinks (lower(phrase), locale)`).Error; err != nil {
+				return err
+			}
+			return tx.Exec(`ALTER TABLE golem15_seo_settings ADD COLUMN autolink_max INTEGER NOT NULL DEFAULT 3`).Error
+		},
+		Rollback: func(tx *gorm.DB) error {
+			if err := tx.Exec(`ALTER TABLE golem15_seo_settings DROP COLUMN IF EXISTS autolink_max`).Error; err != nil {
+				return err
+			}
+			return tx.Exec(`DROP TABLE IF EXISTS golem15_seo_autolinks`).Error
+		},
+	},
+}
+
+func init() {
+	Register(createAutolinks...)
+}