feat: pinned tickets, at hand on the home page and in search

Each person pins up to 20 tickets from the ticket's page («Fijar»). They
show as a strip under the projects on the home page and in the search
palette before typing. Private and without history, like the views of
«my work» (Mongo `pinned_issues`); tickets in the trash or out of reach
are left out, and when the list is full the unreadable ones are dropped
first.

API: GET /api/me/pins, PUT/DELETE /api/issues/{issue}/pin; GraphQL
myPins, pinIssue, unpinIssue and Issue.pinned.

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

apps/api/schema.gql

@@ -662,6 +662,9 @@ type Issue {
 
   """The epic or ticket this one breaks down"""
   parent: IssueParent
+
+  """Whether I pinned it (false without a token)"""
+  pinned: Boolean!
   priority: IssuePriority!
   projectId: ID!
   projectKey: String!
@@ -973,6 +976,11 @@ type Mutation {
   """Mark these as read, or all of them when `ids` is omitted"""
   markNotificationsRead(ids: [ID!]): Boolean!
 
+  """
+  Pin a ticket: keep it at hand on my home page and in search (private, at most 20)
+  """
+  pinIssue(issueId: ID!): Boolean!
+
   """
   Ship the release. Fails while it has unfinished tickets unless force = true.
   """
@@ -1046,6 +1054,9 @@ type Mutation {
   unarchiveProject(projectId: ID!): CommandResult!
   unlinkIssues(input: LinkIssuesInput!): CommandResult!
 
+  """Unpin a ticket"""
+  unpinIssue(issueId: ID!): Boolean!
+
   """The link stops working"""
   unshareDashboard(projectId: ID!): Boolean!
 
@@ -1532,6 +1543,11 @@ type Query {
   """My notifications, newest first, and how many are unread"""
   myNotifications(limit: Int! = 30, unreadOnly: Boolean! = false): MyNotifications!
 
+  """
+  My pinned tickets, most recently pinned first (trashed or out of reach left out)
+  """
+  myPins: [Issue!]!
+
   """Projects where I am a member"""
   myProjects: [Project!]!