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/migrations/0017_featured_discount_codes.sql

@@ -0,0 +1,31 @@
+-- Migration 0017: featured discount codes
+--
+-- Adds a `featured` flag to discount_codes. A "featured" discount is one
+-- the operator wants prominently displayed on the buy page — typically a
+-- launch promotion or a time-limited deal — rather than a normal discount
+-- code that requires the buyer to type it in.
+--
+-- Effect when featured = true:
+--   - The buy page renders the policy's original price struck through
+--     plus the discounted price, with a "LAUNCH SPECIAL" diagonal
+--     corner ribbon and the discount tagline.
+--   - The purchase endpoint auto-applies the discount when no `code`
+--     query param / body field is supplied. Buyers who type a different
+--     code in the form get that code instead (operator-typed codes win
+--     over auto-featured codes).
+--
+-- Activation/eligibility rules are unchanged from non-featured codes:
+-- `active = 1` AND not expired AND below max_uses. So when a featured
+-- code exhausts its 100-use cap, the buy page automatically stops
+-- showing the launch-special ribbon and reverts to the standard
+-- non-discounted price.
+
+ALTER TABLE discount_codes ADD COLUMN featured INTEGER NOT NULL DEFAULT 0;
+
+-- Partial index: featured codes only. Lookups for "the active featured
+-- discount that applies to this policy" hit this index instead of
+-- scanning every discount code. Tiny table either way today, but the
+-- pattern scales.
+CREATE INDEX IF NOT EXISTS idx_discount_codes_featured
+  ON discount_codes(applies_to_policy_id, applies_to_product_id, featured)
+  WHERE featured = 1 AND active = 1;