feat: add the bm:seed command

Validates a whole JSON file (course keys, meeting numbers, values, dates)
and upserts meetings, courses, class sessions, deadlines and readings in
one transaction, matched on their natural identity. Prints a created,
updated and unchanged summary; --dry-run only validates. Ships a small
example fixture with made-up data.

plugin.go

@@ -1,15 +1,19 @@
 package bm
 
 import (
+	"context"
 	"embed"
 	"io/fs"
 
 	"git.golem15.com/golem15/summercms/modules/backpack"
 	"git.golem15.com/golem15/summercms/modules/bonfire"
+	"git.golem15.com/golem15/summercms/modules/lagoon"
 	"git.golem15.com/golem15/summercms/modules/pact"
 	"git.golem15.com/golem15/summercms/modules/party"
+	"git.golem15.com/jakub/sm-bm-plugin/console"
 	"git.golem15.com/jakub/sm-bm-plugin/controllers"
 	"github.com/go-gormigrate/gormigrate/v2"
+	"gorm.io/gorm"
 )
 
 var (
@@ -76,8 +80,11 @@ func (p *Plugin) AdminControllers() []pact.AdminController {
 	return generatedAdminControllers()
 }
 
-// Commands returns the generated commands.
-func (p *Plugin) Commands() []bonfire.Command { return generatedCommands() }
+// Commands returns the generated commands plus bm:seed, which needs the
+// database and so is built here with the plugin's withDB.
+func (p *Plugin) Commands() []bonfire.Command {
+	return append(generatedCommands(), console.SeedCommand(p.withDB))
+}
 
 // AdminFS is the admin YAML the controllers read.
 func (p *Plugin) AdminFS() fs.FS { return adminFS }
@@ -114,6 +121,21 @@ func (p *Plugin) Navigation() []pact.NavigationItem {
 	}}
 }
 
+// withDB runs fn with the application's database: the one the serve command
+// published, or, when a console command runs, one opened from the config for
+// the duration of fn.
+func (p *Plugin) withDB(ctx context.Context, fn func(*gorm.DB) error) error {
+	if gdb, ok := p.app.Lookup[*gorm.DB](); ok && gdb != nil {
+		return fn(gdb)
+	}
+	sqlDB, gdb, err := lagoon.OpenFromApp(ctx, p.app)
+	if err != nil {
+		return err
+	}
+	defer sqlDB.Close()
+	return fn(gdb)
+}
+
 func init() {
 	party.Register(&Plugin{})
 }