merge trails function added (#627)

* merge trails function added

* fix conflict resolve issues

* avoid incorrect authorship when merging trail comments

* require edit access for all selected trails before merge

* fix likes checkbox binding in trail merge modal

* improve error handling

* require editable target and deletable sources for merge

* avoid duplicate trail fetch during merge

* prevent duplicate likes when merging trails

* check photo download responses during trail merge

* add merge completion toast notifications

* cleanup

* small fixes

* move merge code to backend, option to merge single trail selection with similar one, automatic merge for integrations add as option, maintenance page to find and merge similar trails added

* fix build error

* fix

* docu, beautifying, refactoring

---------

Co-authored-by: Flomp <Flomp@users.noreply.github.com>

db/migrations/1772400002_updated_trails_remove_external_fields.go

@@ -0,0 +1,62 @@
+package migrations
+
+import (
+	"github.com/pocketbase/pocketbase/core"
+	m "github.com/pocketbase/pocketbase/migrations"
+)
+
+func init() {
+	m.Register(func(app core.App) error {
+		collection, err := app.FindCollectionByNameOrId("e864strfxo14pm4")
+		if err != nil {
+			return err
+		}
+
+		collection.Fields.RemoveById("sajmiuau")
+		collection.Fields.RemoveById("htr35nha")
+
+		return app.Save(collection)
+	}, func(app core.App) error {
+		collection, err := app.FindCollectionByNameOrId("e864strfxo14pm4")
+		if err != nil {
+			return err
+		}
+
+		if err := collection.Fields.AddMarshaledJSONAt(17, []byte(`{
+			"autogeneratePattern": "",
+			"hidden": false,
+			"id": "sajmiuau",
+			"max": 0,
+			"min": 0,
+			"name": "external_id",
+			"pattern": "",
+			"presentable": false,
+			"primaryKey": false,
+			"required": false,
+			"system": false,
+			"type": "text"
+		}`)); err != nil {
+			return err
+		}
+
+		if err := collection.Fields.AddMarshaledJSONAt(18, []byte(`{
+			"hidden": false,
+			"id": "htr35nha",
+			"maxSelect": 1,
+			"name": "external_provider",
+			"presentable": false,
+			"required": false,
+			"system": false,
+			"type": "select",
+			"values": [
+				"strava",
+				"komoot",
+				"hammerhead"
+			]
+		}`)); err != nil {
+			return err
+		}
+
+		return app.Save(collection)
+	})
+}