feat: move unfinished tickets between releases

- Bulk editing gets «Release…» (open releases or none), and the list
  view a release filter, also reachable from each release («Ver en la
  lista», ?release=).
- Archiving a release asks where its unfinished tickets go, as closing
  a sprint does: ReleaseArchivedEvent carries `moveTo` (an open release
  of the same project, or none) and the saga moves them there; finished
  ones stay. In GraphQL, REST and the MCP's archive_release.
- Chapter 10 lists the next features and the ideas to weigh.

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

apps/api/schema.gql

@@ -648,7 +648,13 @@ type Mutation {
 
   """Add a Pireon user to the project"""
   addProjectMember(input: ProjectMemberInput!): CommandResult!
-  archiveRelease(releaseId: ID!): CommandResult!
+  archiveRelease(
+    """
+    Open release of the same project that takes its unfinished tickets; none: they leave it
+    """
+    moveTo: ID
+    releaseId: ID!
+  ): CommandResult!
 
   """Assign (or unassign with null) a project member"""
   assignIssue(assigneeId: ID, issueId: ID!): CommandResult!