chore: prune unused apps and services for the moeka fork

- Remove stage-tamagotchi, stage-pocket, server, and engine workspaces with their workflows, addons, and docs
- Switch the toolchain from pnpm to bun, replace lockfiles with bun.lock
- Rewrite remaining product references to Moeka

turbo.json

@@ -8,10 +8,6 @@
     "typecheck": {
       "dependsOn": ["^typecheck"],
       "inputs": ["$TURBO_DEFAULT$", "$TURBO_ROOT$/tsconfig.json"]
-    },
-    "@proj-airi/electron-vueuse#build": {
-      "dependsOn": ["@proj-airi/electron-eventa#build"],
-      "outputs": ["dist/**"]
     }
   }
 }