[Gaubee]

Summary

• refactor miniapp runtime into fsm* state transitions and domBind* bindings
• keep background miniapps mounted in DOM (no iframe teardown), use visibility + interactivity control only
• simplify stack view to shadcn item list and wire activation/minimize behavior
• fix activation to enforce single-foreground by set intersection/difference and bump target z-order
• add runtime/container/stack-view tests including activation regression coverage

Validation

• pnpm check
• pnpm -s vitest run src/services/miniapp-runtime/__tests__/activate-app.test.ts src/services/miniapp-runtime/__tests__/runtime-state-machine.test.ts src/services/miniapp-runtime/__tests__/container.test.ts src/components/ecosystem/miniapp-stack-view.test.tsx