Add crown cosmetic type (#4618)

## What

Adds **crowns** as a new cosmetic category, wired end-to-end like
flags/skins, plus a Crowns tab in the lobby cosmetics modal (#4617).

Catalog shape in cosmetics.json:

```json
"crowns": {
  "gold_crown": {
    "name": "gold_crown",
    "url": "...",
    "affiliateCode": null,
    "product": null,
    "priceHard": 5,
    "artist": "...",
    "rarity": "common"
  }
}
```

## Changes

- **Core**: `CrownSchema` + optional `crowns` record in
`CosmeticsSchema`; `crownName` in `PlayerCosmeticRefs`; resolved `crown:
{ name, url }` in `PlayerCosmetics`
- **Server**: `isCrownAllowed` in the privilege checker — requires a
`crown:*` or `crown:<name>` flare, resolves the ref to the catalog URL
- **Client**: crown selection persisted under the `crown` localStorage
key (stale/unowned selections self-clear), `crownRelationship` +
resolve/refs wiring, `"crown"` purchase type, Crowns tab in the store,
and a Crowns tab in the cosmetics modal (owned crowns + Default tile;
selecting persists and keeps the modal open)
- **i18n**: `store.crowns`, `store.no_crowns`
- Tests for schema parsing, privilege checks, and cosmetic resolution

## Not in this PR

- In-game rendering of `player.cosmetics.crown` (name pass /
leaderboards / player panel)
- API-side support (`/shop/purchase` accepting `cosmeticType: "crown"`,
granting `crown:<name>` flares, serving `crowns` in cosmetics.json)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

src/client/components/CosmeticButton.ts

@@ -1,6 +1,7 @@
 import { html, LitElement, nothing, TemplateResult } from "lit";
 import { customElement, property, state } from "lit/decorators.js";
 import {
+  Crown,
   Effect,
   Flag,
   isNukeExplosionEffect,
@@ -91,6 +92,9 @@ export class CosmeticButton extends LitElement {
     if (this.activeResolved.type === "effect") {
       return translateCosmetic("effects", c.name);
     }
+    if (this.activeResolved.type === "crown") {
+      return translateCosmetic("crowns", c.name);
+    }
     return translateCosmetic("flags", c.name);
   }
 
@@ -209,6 +213,25 @@ export class CosmeticButton extends LitElement {
       ></trail-swatch>`;
     }
 
+    if (this.activeResolved.type === "crown") {
+      const c = this.activeResolved.cosmetic as Crown | null;
+      if (c === null) {
+        // "Default" (none) tile — selecting it clears the crown.
+        return html`<div
+          class="w-full h-full flex items-center justify-center text-white/40 text-xs uppercase"
+        >
+          ${translateText("territory_patterns.pattern.default")}
+        </div>`;
+      }
+      return html`<img
+        src=${c.url}
+        alt=${c.name}
+        class="w-full h-full object-contain pointer-events-none"
+        draggable="false"
+        loading="lazy"
+      />`;
+    }
+
     if (this.activeResolved.type === "pack") {
       const pack = this.activeResolved.cosmetic as Pack;
       const isHard = pack.currency === "hard";