Document beta release workflow

Author: coder13

AGENTS.md

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 Use space-y instead of mt-2 for better spacing between elements.
 Always use spacing in multiples of 2 unless you need to use odd spacing for a specific reason. This helps maintain visual consistency across the app.
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+## Branch and deployment workflow
+
+- `main` is the GitHub default branch and Netlify production branch.
+- `beta` is the permanent integration and beta-testing branch.
+- Feature and fix PRs should target `beta`, not `main`.
+- Production releases happen by opening or updating the deploy PR from `beta` into `main`.
+- Use the manual GitHub Actions `Deploy` workflow to create or update the `beta` -> `main` release PR.
+- PRs into `main` are guarded and should only come from `beta`.