feat: live updates on shared meal plans

Two separate components (the owner's own week view and collaborators'
shared view) hit two different API surfaces for the same underlying
entries, so neither ever saw the other's edits without a manual
reload. Both now poll a new lean GET on their respective entries
routes every 4s, merged with the same dirty-until-ref guard used for
shopping lists so a poll can't stomp an in-flight local edit.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/lib/changelog.ts

@@ -1,5 +1,5 @@
 // Mirrors CHANGELOG.md at the repo root — update both together.
-export const APP_VERSION = "0.17.0";
+export const APP_VERSION = "0.18.0";
 
 export type ChangelogEntry = {
   version: string;
@@ -11,6 +11,13 @@ export type ChangelogEntry = {
 };
 
 export const CHANGELOG: ChangelogEntry[] = [
+  {
+    version: "0.18.0",
+    date: "2026-07-13 22:16",
+    added: [
+      "**Live updates on shared meal plans**: entries added, removed, or cleared by a collaborator now appear automatically, both on the owner's own week view and everyone else's shared view.",
+    ],
+  },
   {
     version: "0.17.0",
     date: "2026-07-13 22:06",