feat: an ordered backlog

A Backlog tab lists the tickets still to start in the order the team will
take them; drag them, or use the arrows, to reorder. Moving a ticket only
rewrites that ticket's rank, read from the event store, and board columns
follow the same order.

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

apps/api/schema.gql

@@ -242,6 +242,11 @@ type Issue {
   priority: IssuePriority!
   projectId: ID!
   projectKey: String!
+
+  """
+  Place in the backlog and in its board column (ascending, compare as text)
+  """
+  rank: String!
   release: ReleaseRef
   reporter: UserRef!
 
@@ -281,6 +286,7 @@ input IssueFilterInput {
 
   """Matches key, title or description"""
   search: String
+  sort: IssueSort = RECENT
   statuses: [String!]
   types: [String!]
   unassigned: Boolean
@@ -322,6 +328,12 @@ enum IssuePriority {
   MEDIUM
 }
 
+"""RECENT: last updated first. RANK: backlog order."""
+enum IssueSort {
+  RANK
+  RECENT
+}
+
 type IssueTypeOption {
   archived: Boolean!
   color: String!
@@ -400,6 +412,9 @@ type Mutation {
   """
   publishRelease(force: Boolean! = false, releaseId: ID!): CommandResult!
 
+  """Move a ticket in the backlog, between two others of the same project"""
+  rankIssue(input: RankIssueInput!): CommandResult!
+
   """
   Remove a file from a ticket (whoever uploaded it, or an owner/admin). Upload with the REST API.
   """
@@ -641,6 +656,15 @@ type Query {
   users(limit: Int! = 20, search: String! = ""): [User!]!
 }
 
+input RankIssueInput {
+  """The ticket that ends up right above (null: the top)"""
+  aboveIssueId: ID
+
+  """The ticket that ends up right below (null: the bottom)"""
+  belowIssueId: ID
+  issueId: ID!
+}
+
 type Release {
   """Scope vs finished tickets, day by day"""
   burnup: ReleaseBurnup!