Remove generated files from git tracking

- Add api/proto/generated/ to .gitignore (protobuf generated files)
- Add internal/ent/ and ent/ to .gitignore (Ent ORM generated files)
- Remove all generated files from git tracking
- Generated files can be regenerated with 'make generate-proto' and 'make generate-ent'

ent/schema/user.go

@@ -1,18 +0,0 @@
-package schema
-
-import "entgo.io/ent"
-
-// User holds the schema definition for the User entity.
-type User struct {
-	ent.Schema
-}
-
-// Fields of the User.
-func (User) Fields() []ent.Field {
-	return nil
-}
-
-// Edges of the User.
-func (User) Edges() []ent.Edge {
-	return nil
-}