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/domain/src/lib/read-models/notification.read-model.ts

@@ -14,6 +14,8 @@ export enum NotificationKind {
   MENTIONED = 'MENTIONED',
   /** Someone answered a comment of yours. */
   REPLIED = 'REPLIED',
+  /** A bug report or an idea came in through a project's public form. */
+  PROPOSED = 'PROPOSED',
   /** A ticket you follow changed. */
   WATCHED = 'WATCHED',
   /** You were added to a project. */