v6.1.0 - Staging environment and dev → stg → main flow

Highlights

• 🌿 Branch flow: dev (default) → stg → main. Work branches merge into dev, and releases are tagged on main
• 🧪 Staging environment: .env.stg.example, stg:* scripts, and a staging EAS build profile (internal distribution, Release build)
• 📦 prod:* scripts: every dev:* script now has stg:* and prod:* versions. prod:deploy:web deploys to the production alias
• 🧰 Agent skills: manage-prs gains a promote action, and all skills follow the new branch flow

Breaking changes

• ENV values changed from development, staging, production to dev, stg, prod. Update ENV in your .env.* files and rebuild native apps, because the app config is embedded at build time
• stg:* scripts need a staging EAS project. Set its ID in EXPO_PROJECT_ID of .env.stg

Other changes

• CI runs on pushes to dev, stg, and main

Full Changelog: v6.0.0...v6.1.0 (#109, #110)