[FEAT] Rebranding: rename LevelUp to ClimbStack #153

Is your feature request related to a problem? Please describe.

The repository and organization have been rebranded to ClimbStack. Several references across the codebase, documentation, templates, package configuration, and app metadata still refer to "LevelUp".

Describe the solution you'd like

Update all occurrences and references from "LevelUp" to "ClimbStack":

• App configuration and package metadata (package.json, app.json)
• Documentation, README, and Roadmap
• GitHub templates and workflows
• Screen titles, headers, translations, and UI strings

Describe alternatives you've considered

Keeping the legacy name in parts of the project, which leads to confusion and brand inconsistency.

Additional Context

Organization transfer to ClimbStack.

Note: This issue was created with the assistance of an AI agent (Antigravity).