share button for recommending the Platform

[tenkus47]

1. User Story

As an influencer
I need a general "Share App" button in the settings menu,
In order to recommend the platform to my contacts who might benefit from Buddhist practice.

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2. Definition of Done (DoD)

• Location: The button is easily accessible in the Settings section.
• Output Format: Generates a standard Link Preview card containing:
  • App Icon
  • App Title
  • Catchy slogan (e.g., "Your Buddhist App")
• Target: The shared link directs purely to the App Store download landing page.
• QR Code Feature: The user can toggle/tap to display a QR code on their screen for a friend to scan immediately in person.