feat(imports): add real pricing and subscription collectors

Add plan catalog and subscription schema support, seed baselines, and real importers for core domestic subscriptions plus stable official pricing sources.

This commit also hardens the shared fetch layers so the importers can support live collection and database writes instead of relying on manual placeholders alone.

scripts/catalog_verification_common.go

@@ -0,0 +1,56 @@
+//go:build llm_script
+
+package main
+
+import (
+	"database/sql"
+	"fmt"
+	"time"
+
+	_ "github.com/lib/pq"
+)
+
+type catalogVerificationRecord struct {
+	CatalogCode string
+	SourceURL   string
+	SourceTitle string
+	PlanStatus  string
+	Notes       string
+}
+
+type catalogVerificationImportConfig struct {
+	URL     string
+	Fixture string
+	DryRun  bool
+	Timeout time.Duration
+}
+
+func upsertCatalogVerificationRecords(db *sql.DB, records []catalogVerificationRecord) error {
+	if len(records) == 0 {
+		return fmt.Errorf("catalog verification records are empty")
+	}
+	for _, record := range records {
+		result, err := db.Exec(
+			`UPDATE plan_catalog_inventory
+			SET source_url = $2,
+			    source_title = $3,
+			    plan_status = $4,
+			    notes = $5,
+			    last_checked_at = CURRENT_TIMESTAMP,
+			    updated_at = CURRENT_TIMESTAMP
+			WHERE catalog_code = $1`,
+			record.CatalogCode, record.SourceURL, record.SourceTitle, record.PlanStatus, record.Notes,
+		)
+		if err != nil {
+			return fmt.Errorf("update plan_catalog_inventory %s: %w", record.CatalogCode, err)
+		}
+		rowsAffected, err := result.RowsAffected()
+		if err != nil {
+			return fmt.Errorf("rows affected for %s: %w", record.CatalogCode, err)
+		}
+		if rowsAffected == 0 {
+			return fmt.Errorf("catalog_code %s not found in plan_catalog_inventory", record.CatalogCode)
+		}
+	}
+	return nil
+}