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

.github/labels.yml

@@ -1,9 +1,3 @@
-- name: 'apps/stage-pocket'
-  description: 'Mobile App: iOS / Android'
-  color: 'b8d5ff'
-- name: 'apps/stage-tamagotchi'
-  description: 'Desktop App: Windows & macOS & Linux'
-  color: 'a1f7ef'
 - name: 'apps/stage-web'
   description: 'Web App: PWA & Browser'
   color: 'abedff'
@@ -137,7 +131,7 @@
   description: 'Scope related to providers we support'
   color: '4468eb'
 - name: 'scope/server-api'
-  description: 'Scope related to the server api we maintained, the public service of AIRI'
+  description: 'Scope related to the server api we maintained, the public service of Moeka'
   color: '4468eb'
 - name: 'scope/ui'
   description: 'Scope related to UI/UX, or interface improve, perf, and bugs'