refactor: convert to bun workspaces monorepo

- Move web app into apps/web/
- Create packages/shared/ with shared types
- Create plugins/decky-vault/ scaffold
- Root package.json manages workspaces only

apps/web/lib/api/game-stub.ts

@@ -0,0 +1,33 @@
+import { Elysia, t } from "elysia"
+import { ensureSteamGame } from "@/lib/steam/sync"
+
+export const gameStubRoutes = new Elysia({ prefix: "/games", detail: { tags: ["Games"] } }).post(
+  "/stub",
+  async ({ body, set }) => {
+    const result = await ensureSteamGame(body.steamAppId)
+
+    if (!result.game) {
+      set.status = 500
+      return { error: "Failed to create or retrieve game" }
+    }
+
+    // If game already existed, return 200 with created:false
+    if (!result.created) {
+      return { game: result.game, created: false }
+    }
+
+    // If sync failed but stub exists, still return 201 with error info
+    if (result.error) {
+      set.status = 201
+      return { game: result.game, created: true, syncError: result.error }
+    }
+
+    set.status = 201
+    return { game: result.game, created: true }
+  },
+  {
+    body: t.Object({
+      steamAppId: t.Number(),
+    }),
+  },
+)