feat: attachments on tickets and comments

Files are uploaded over REST, stored on disk (a volume in Docker) and
recorded on the ticket as events; the bytes are written first, so no
attachment ever points at a missing file. Only images, video, audio, PDF
and plain text are shown inline, everything with nosniff and a sandbox CSP.
The web shows thumbnails, uploads by drag and drop or by pasting a
screenshot, and attaches files to new comments.

Also adds `nx run api:contracts`, which writes schema.gql and
openapi.json without starting the API or any database.

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

libs/web/tracker/application/src/lib/events/issue.events.ts

@@ -29,7 +29,21 @@ export const issuePageEvents = eventGroup({
       issueId: string;
       releaseId: string | null;
     }>(),
-    commentAddRequested: type<{ issueId: string; body: string }>(),
+    commentAddRequested: type<{
+      issueId: string;
+      body: string;
+      /** Uploaded under the new comment once it exists. */
+      files?: File[];
+    }>(),
+    attachRequested: type<{
+      issueId: string;
+      files: File[];
+      commentId?: string | null;
+    }>(),
+    attachmentRemoveRequested: type<{
+      issueId: string;
+      attachmentId: string;
+    }>(),
     commentEditRequested: type<{ commentId: string; body: string }>(),
     commentDeleteRequested: type<{ commentId: string }>(),
   },