Add Rarity to cosmetic items (#3587)

## Description:


https://github.com/user-attachments/assets/f2216dec-72aa-497a-89cc-169c2a40021e


* Fortnite-style rarity system for cosmetics: New CosmeticContainer
component applies tier-based visual styling (gradient backgrounds,
glowing borders, hover effects) to flag and pattern cards across 5
rarity tiers: Common, Uncommon, Rare, Epic, and Legendary
* Legendary hover effects: Scale-up animation, pulsing orange glow,
shimmer sweep, rotating border sweep, corner sparkles, and screen
dimming backdrop
* Epic hover effects: Purple shimmer sweep glint on hover
* Purchase button overhaul: Green ember particles on container hover
(non-common only), 40-particle burst stream on button hover, pulsating
green glow, shimmer streak animation, and loading spinner on click
* Clickable cosmetic cards: Clicking anywhere on a purchasable card (not
just the purchase button) triggers the purchase flow
* Refactored components: ArtistInfo renamed to CosmeticInfo (now shows
rarity and color palette in tooltip),
* Forward-compatible rarity schema: rarity field uses .or(z.string()) so
unknown backend values won't break the client


## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

evan

tests/Privilege.test.ts

@@ -43,6 +43,7 @@ const flagCosmetics = {
       url: "https://example.com/cool.png",
       affiliateCode: null,
       product: { productId: "prod_1", priceId: "price_1", price: "$4.99" },
+      rarity: "common",
     },
   },
 };