Introduce xstate v5 and @xstate/react to manage user authentication and profile state. Implement userMachine with actors for initialization, fetching, and logout operations, along with actions for updating user data and clearing state.
Relocate the Result type from `@/data/result` to `@/utils/result` and
replace the discriminated-union API (`kind`/`value`) with a simpler
boolean-based API (`success`/`data`) across all repositories and
storage classes for improved readability and consistency.
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