FR: Add BEAM (Mimblewimble privacy coin) #1471

Is Problem

BEAM is a Mimblewimble privacy coin (mainnet since January 2019, with confidential assets). Stack Wallet already supports two other Mimblewimble coins, Epic Cash and MWC, but not BEAM.

Solution

I maintain Campfire for BEAM (https://github.com/vsnation/campfire-beam). It is a fork of Campfire, which is built on Stack Wallet, with BEAM added as a coin, and it ships builds for macOS, Android, Linux and Windows. I would like to bring BEAM support to Stack Wallet itself, shaped the way you add coins:

• BEAM's core in its own plugin repository (flutter_libbeam), built from BEAM's release tag during the app build, like the Epic Cash and MWC plugins, with optional SHA-256-pinned prebuilts.
• A first PR with the coin only: wallet, sync, send/receive/history, node settings and backups, behind an on/off flag, tested inside the multi-coin app.
• Later, separate PRs only if you want them: confidential assets as tokens, then extras such as BEAM's DEX and name service. Campfire-only parts (branding, the web wallet) stay out.

Before opening anything I would like to know:

1. Would you accept BEAM?
2. Should a PR target staging, or a feature branch you create for it?
3. Is there anything you require beyond CI (formatting and tests)? For example platforms (macOS Intel, 32-bit Android) or maintenance after the merge, such as BEAM hard forks.

Alternatives

Keep BEAM only in the fork. That works for BEAM users, but they miss Stack Wallet's other coins, and the fork has to keep merging Stack Wallet's changes.

Context

BEAM's core is C++ under Apache-2.0: https://github.com/BeamMW/beam. Its latest hard fork was in June 2026, and the fork already follows it.