add docs

doc/db/planned.mermaid

@@ -0,0 +1,56 @@
+classDiagram
+    class TripType {
+        +int id
+        +string name
+        +string desc
+        +string question
+        +string icon
+    }
+
+    class TripDetails {
+        +int id
+        +string planned_starting_time
+        +int max_people
+        +string day
+        +bool allow_guests
+        +string notes
+        +bool always_show
+        +bool is_locked
+        +int trip_type_id
+    }
+
+    class PlannedEvent {
+        +int id
+        +string name
+        +int planned_amount_cox
+        +int trip_details_id
+        +string created_at
+    }
+
+    class Trip {
+        +int id
+        +int cox_id
+        +int trip_details_id
+        +int planned_event_id
+        +string created_at
+    }
+
+    class UserTrip {
+        +int user_id
+        +string user_note
+        +int trip_details_id
+        +string created_at
+    }
+
+    class User {
+      ...
+    }
+
+
+    TripType "1" -- "*" TripDetails
+    TripDetails "1" -- "*" PlannedEvent
+    Trip "*" -- "1" TripDetails
+    Trip "*" -- "1" PlannedEvent
+    UserTrip "*" -- "1" TripDetails
+    Trip "*" -- "1" User : cox
+    UserTrip "*" -- "1" User