2.0.0: changelog and skill docs for slugs and environments

Claude-Session: https://claude.ai/code/session_01SMCvdwDmuxoaqGgvGBLk1V

skills/rudder-web-sdk/reference/stores.md

@@ -13,7 +13,7 @@ client.stores.onChange(cb);
 await client.stores.load() / .reload();
 
 // Direct purchase (bypassing handles):
-await client.stores.purchase(storeSlug, offerId, options?);
+await client.stores.purchase(storeSlug, offerSlug, options?);
 ```
 
 ## Handles
@@ -28,7 +28,8 @@ class ShopHandle {
 }
 
 class OfferHandle {
-  readonly id: string;
+  readonly id: string;    // authoring id, differs between staging and prod
+  readonly slug: string;  // stable across environments — what purchases use
   readonly name?: string;
   readonly price?: OfferPrice;        // { amount?: number; currency?: string }
   readonly contents: OfferContent[];  // { amount?: number; itemId?: string }[]
@@ -48,15 +49,15 @@ interface PurchaseOfferResponse {
 
 ## Purchase semantics
 
-- `stores.purchase(storeSlug, offerId, options?)` and `offer.buy(options?)` are
-  the same executor; handles just bind the slug/id.
+- `stores.purchase(storeSlug, offerSlug, options?)` and `offer.buy(options?)` are
+  the same executor; handles just bind the store slug and the offer slug.
 - When `options.idempotencyKey` is omitted the SDK generates
   `crypto.randomUUID()` per call — safe retries require passing your own key.
 - On success the executor invalidates `player`, `inventory`, and `stores`, so
   subscribers observe fresh wallet/inventory/store data immediately.
 - Check `response.success` / `response.error` — a failed purchase is a resolved
   response, not necessarily a thrown error.
-- Purchase metrics (`purchase.offer:<offerId>`, `purchase.item:<itemId>`) are
+- Purchase metrics (`purchase.offer:<offerSlug>`, `purchase.item:<itemId>`) are
   reported to quests automatically server-side — do not report them manually
   (see `reference/quests.md`).
 
@@ -71,10 +72,11 @@ interface Store {
 }
 interface Offer {
   contents?: OfferContent[]; createdAt?: string; id?: string;
-  maxPurchases?: number; name?: string; price?: OfferPrice; updatedAt?: string;
+  maxPurchases?: number; name?: string; price?: OfferPrice; slug?: string;
+  updatedAt?: string;
 }
 ```
 
 `ShopHandle`/`OfferHandle` throw a plain `Error` if constructed from a store
-without `slug` / an offer without `id` — in practice the domain only builds
-handles from server data that has both.
+without `slug` / an offer without `id` or `slug` — in practice the domain only
+builds handles from server data that has all of them.