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>

apps/api/openapi.json

@@ -10997,6 +10997,10 @@
             "type": "number",
             "description": "How many want it done"
           },
+          "voted": {
+            "type": "boolean",
+            "description": "Whether I voted for it (false without a token)"
+          },
           "rank": {
             "type": "string",
             "description": "Place in the backlog and its board column (ascending, as text)"
@@ -11064,6 +11068,7 @@
           "parent",
           "blockedBy",
           "votes",
+          "voted",
           "rank",
           "checklist",
           "trashedAt",
@@ -12673,6 +12678,7 @@
           "COMMENTED",
           "MENTIONED",
           "REPLIED",
+          "PROPOSED",
           "WATCHED",
           "ADDED_TO_PROJECT",
           "REMINDER"