feat: templates per ticket type

Each ticket type can carry a starting description and a checklist, edited
in the project settings. New tickets of that type get the description
when they come without one and always get the checklist; the new ticket
form says what the template will add.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/api/schema.gql

@@ -491,12 +491,27 @@ enum IssueSort {
   RECENT
 }
 
+"""What a new ticket of the type starts with"""
+type IssueTemplate {
+  """Steps added to every new ticket"""
+  checklist: [String!]!
+
+  """Used when the ticket comes without a description"""
+  description: String
+}
+
+input IssueTemplateInput {
+  checklist: [String!]! = []
+  description: String
+}
+
 type IssueTypeOption {
   archived: Boolean!
   color: String!
   icon: String!
   id: String!
   name: String!
+  template: IssueTemplate
 }
 
 input IssueTypeOptionInput {
@@ -505,6 +520,7 @@ input IssueTypeOptionInput {
   icon: String!
   id: String!
   name: String!
+  template: IssueTemplateInput
 }
 
 enum LinkDirection {