Support policies.json on Android to disable Private Browsing / Incognito mode

[Ceruledge]

The Problem:
On desktop Firefox, users and administrators have complete control using policies.json. Setting "DisablePrivateBrowsing": true cleanly removes the private browsing option, shortcuts, and about:privatebrowsing.

On Firefox for Android, there is zero enterprise policy support. As a result, there is currently no way to disable or hide the private browsing tab tray. This single omission forces parents managing children's devices, as well as adult power users seeking intentional friction for late-night self-discipline, to abandon Firefox in favor of Chromium-based browsers that support device management rules natively.

The Proposed Solution:
Enable Firefox for Android to ingest enterprise policy definitions (specifically desktop's DisablePrivateBrowsing policy) without cluttering the consumer Settings menu. This can be achieved by:
1. Allowing Firefox to read a local policies.json file placed in an accessible storage path, or via an "Import Policy" option in advanced settings.

2. Supporting standard Android Enterprise Managed Configurations (AppRestrictions).

Why This Matters for Firefox & Long-Term Market Share:
- Securing the Generational Funnel: When a child is introduced to Firefox from the start, they simply grow up using Firefox by default. However, when parents cannot enforce basic boundaries on mobile, they are forced to install Chrome instead. Once a child builds years of muscle memory, autofill, and habits inside Chrome, they almost never switch to Firefox as adults. Allowing parents to disable private browsing keeps kids inside the Firefox ecosystem from day one.

- Zero UI Clutter: Satisfies user demand for disabling private browsing without needing to design, translate, or maintain complex parental toggle menus in the primary UI.

- User Agency & Self-Discipline: Gives users true sovereignty to configure their browser environment to suit their personal discipline, accountability, and administrative needs.