v0.2.0:16 — Launch-special discount codes + marketing bullets

Major feature release.

Featured (launch-special) discount codes:
  - New 'featured' flag on discount_codes (migration 0017). When true,
    the buy page renders a diagonal LAUNCH SPECIAL ribbon + slashed
    original price + new price for every applicable tier. Purchase
    endpoint auto-applies the discount for buyers who don't type a
    code. Operator-typed codes still win.
  - find_applicable_featured_discount repo helper: most-specific match
    (policy > product > global), tiebreak by created_at.
  - GET /v1/products/<slug>/policies now returns featured_discount per
    policy with the post-discount price computed server-side. SDK
    consumers + the dynamic pricing page get this for free.

Marketing bullets on policies:
  - metadata.marketing_bullets — operator-controlled copy that renders
    as additional checkmarks above the entitlement bullets on both the
    admin grid tier card and the buy page tier. For things like 'Up
    to 5 products' or 'BTCPay integration' that aren't real
    entitlement gates.
  - Authored via textarea on draft + edit policy forms.

UI:
  - 'Most popular' checkbox now on the draft tier card (was edit-only).
  - Discount codes tab grouped by product (matching Licenses /
    Subscriptions tabs). Each code row gets a 'featured' badge when
    flagged.

All 87 tests still pass. Migration is additive, no SDK changes,
backwards-compatible.

licensing-service/src/models.rs

@@ -324,6 +324,13 @@ pub struct DiscountCode {
     pub referrer_label: Option<String>,
     pub description: String,
     pub active: bool,
+    /// When `true`, the buy page renders this code as a public "launch
+    /// special" — striking the original price, showing the discounted
+    /// price, with a "LAUNCH SPECIAL" diagonal ribbon. The purchase
+    /// endpoint auto-applies it for buyers who don't type any code.
+    /// Operator-typed codes still win if the buyer manually enters one.
+    #[serde(default)]
+    pub featured: bool,
     pub created_at: String,
     pub updated_at: String,
 }