feat: outgoing webhooks

Owners and admins can point a project at other systems: a signed JSON
POST (HMAC-SHA256 of the body) when tickets, comments, releases or sprints
change, filtered by event or family. Deliveries are retried a couple of
times, the last one is shown, and a ping can be sent from the settings.
Private addresses are refused unless WEBHOOKS_ALLOW_PRIVATE is set.

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

apps/api/schema.gql

@@ -190,6 +190,13 @@ input CreateSprintInput {
   startDate: String!
 }
 
+input CreateWebhookInput {
+  """Event names, family.* or *"""
+  events: [String!]!
+  projectId: ID!
+  url: String!
+}
+
 type CreatedResolved {
   created: Int!
   resolved: Int!
@@ -465,6 +472,7 @@ type Mutation {
 
   """Plan a sprint (owners and admins)"""
   createSprint(input: CreateSprintInput!): CommandResult!
+  createWebhook(input: CreateWebhookInput!): WebhookCreated!
 
   """Author or project admin"""
   deleteComment(commentId: ID!): CommandResult!
@@ -479,6 +487,7 @@ type Mutation {
 
   """Delete a sprint that never started; its tickets go back to the backlog"""
   deleteSprint(sprintId: ID!): CommandResult!
+  deleteWebhook(webhookId: ID!): Boolean!
   disableGitIntegration(projectId: ID!): Boolean!
   editComment(body: String!, commentId: ID!): CommandResult!
 
@@ -522,6 +531,9 @@ type Mutation {
 
   """Start a planned sprint (only one under way per project)"""
   startSprint(sprintId: ID!): CommandResult!
+
+  """Send a ping now and tell how it went"""
+  testWebhook(webhookId: ID!): WebhookDelivery!
   unlinkIssues(input: LinkIssuesInput!): CommandResult!
 
   """Stop following a ticket"""
@@ -539,6 +551,7 @@ type Mutation {
   updateProjectSettings(projectId: ID!, settings: ProjectSettingsInput!): CommandResult!
   updateRelease(input: UpdateReleaseInput!): CommandResult!
   updateSprint(input: UpdateSprintInput!): CommandResult!
+  updateWebhook(input: UpdateWebhookInput!): Webhook!
 
   """
   Follow a ticket: be told when it moves, is reassigned or gets a comment
@@ -776,6 +789,10 @@ type Query {
 
   """Search users by name or email (to assign / add members)"""
   users(limit: Int! = 20, search: String! = ""): [User!]!
+
+  """Event names a webhook can subscribe to (also family.* and *)"""
+  webhookEvents: [String!]!
+  webhooks(projectId: ID!): [Webhook!]!
 }
 
 input RankIssueInput {
@@ -1053,6 +1070,13 @@ input UpdateSprintInput {
   startDate: String
 }
 
+input UpdateWebhookInput {
+  active: Boolean
+  events: [String!]
+  url: String
+  webhookId: ID!
+}
+
 """User managed by the Pireon identity server"""
 type User {
   email: String!
@@ -1066,6 +1090,39 @@ type UserRef {
   name: String!
 }
 
+"""
+Where the project tells another system what happened (signed POST, HMAC-SHA256)
+"""
+type Webhook {
+  active: Boolean!
+  createdAt: String!
+  createdBy: UserRef!
+
+  """Event names, family.* or *"""
+  events: [String!]!
+  id: ID!
+  lastDelivery: WebhookDelivery
+  projectId: ID!
+  url: String!
+}
+
+type WebhookCreated {
+  id: ID!
+
+  """Signs every delivery. Shown only now: keep it."""
+  secret: String!
+}
+
+type WebhookDelivery {
+  at: String!
+  error: String
+  event: String!
+  ok: Boolean!
+
+  """HTTP status"""
+  status: Int
+}
+
 type WorkflowStatus {
   """No new tickets or transitions into it"""
   archived: Boolean!