feat: version history as 10th feature flag, richer upgrade prompts, close unguarded photo-import tab (v0.80.0)

Recipe version history is now gated like the other 9 per-tier features (enabled by default, locked-vs-hidden treatment via isFeatureAvailableAnyTier). UpgradeDialog now shows a tagline + concrete bullet list per feature instead of one generic sentence.

Also closes a real gap: the AI-generate dialog's Photo tab hit /api/v1/ai/import-photo directly with no tier check in the UI (server route was already correctly gated) — a locked-out user could fill it in and hit a dead-end error instead of an upgrade prompt. Now threaded through the same lock/hide props as the dedicated PhotoImportButton.

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

apps/web/lib/feature-flags.ts

@@ -23,6 +23,12 @@ export const FEATURE_DEFINITIONS = [
     description: "AI-suggested side dish / meal pairings for a recipe.",
     defaultEnabled: true,
   },
+  {
+    key: "version_history",
+    label: "Recipe version history",
+    description: "Snapshots of a recipe's prior versions, with diff/compare and restore.",
+    defaultEnabled: true,
+  },
   // The following ship disabled by default (2026-07-24) — turn on per tier
   // from this page once ready, rather than a code change.
   {