feat: locked-feature upgrade prompts route to billing + track upgrade interest (v0.81.0)

UpgradeDialog's CTA now sends users to Settings > Billing (with a feature-specific banner) instead of a generic support-ticket prefill, and fires a best-effort tracking beacon recording which feature triggered the click. New feature_upgrade_clicks table + Admin > Insights chart ("Most-requested locked features") gives admins visibility into which locked features actually drive upgrade interest.

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 = "0.80.0";
+export const APP_VERSION = "0.81.0";
 
 export type ChangelogEntry = {
   version: string;
@@ -11,6 +11,14 @@ export type ChangelogEntry = {
 };
 
 export const CHANGELOG: ChangelogEntry[] = [
+  {
+    version: "0.81.0",
+    date: "2026-07-24 17:15",
+    added: [
+      "Locked-feature upgrade prompts now route straight to Settings > Billing (with a banner naming the feature you were trying to use) instead of a generic support-ticket form.",
+      "Every upgrade-prompt click is now recorded (feature key only, best-effort) so Admin > Insights can show which locked features are actually driving upgrade interest, in a new \"Most-requested locked features\" chart.",
+    ],
+  },
   {
     version: "0.80.0",
     date: "2026-07-24 16:45",