feat: chat stickers

lib/sadhna.ts

@@ -111,9 +111,13 @@ export type SadhnaReward = {
 
 /** A reward earned at a streak milestone (a multiple of 7 days). */
 export type SadhnaRewardGrant = {
-  milestone: number;
+  /** The streak day this was earned on. Null for an occasional gift. */
+  milestone: number | null;
   granted_at: string;
   reward: SadhnaReward;
+  source: "streak" | "gift";
+  /** False while a gift is still wrapped — the gallery blurs those. */
+  opened: boolean;
 };
 
 // ─── API ───────────────────────────────────────────────────────────────
@@ -140,6 +144,12 @@ export const sadhna = {
   rewards: () =>
     call<{ collected: SadhnaRewardGrant[]; total: number }>("/sadhna/rewards"),
 
+  /** Open one gift, after its celebration is dismissed. Idempotent. */
+  openGift: (rewardKey: string) =>
+    call<void>(`/sadhna/rewards/gifts/${encodeURIComponent(rewardKey)}/open`, {
+      method: "POST",
+    }),
+
   /** Acknowledge pending celebrations after showing the confetti. */
   ackRewards: () => call<void>("/sadhna/rewards/ack", { method: "POST" }),