feat: steadier live updates and notices for public proposals

- The web pings the live connection, reconnects when it goes quiet and
  reloads what each screen shows after reconnecting.
- Dropping a card on a column it cannot go to puts it back.
- Owners and admins get a notice when a proposal arrives.
- The proposal limit lives in Redis, so it holds across instances.
- REST tells whether I voted; pasted images leave the attachment list.
- Deleting a project removes its Git integration; no lint warnings left.
- Reactions and the blocked badge are components of their own.
- Docs: what is done and what is left (chapter 10), Word and PDF.

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

libs/api/tracker/presenters/src/lib/http/sprints.controller.ts

@@ -223,7 +223,10 @@ export class SprintsController {
       limit: query.limit,
       offset: query.offset,
     });
-    return { ...page, items: await this.refs.issueDtos(page.items) };
+    return {
+      ...page,
+      items: await this.refs.issueDtos(page.items, viewerOf(me)),
+    };
   }
 
   @Put('issues/:issue/sprint')