Document required Gitea release publication workflow

AGENTS.md

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+# Release workflow
+
+For every new app version, publish the latest built ARM IPK as an attachment to
+a Gitea release in https://gitea.adnau.de/matze19999/HyperDRM.
+
+- Complete relevant checks and keep app/package versions consistent.
+- Build the IPK and regenerate the package manifest.
+- Push the version's source and package to `main`.
+- Create a release tagged `v<app version>` at the corresponding commit, with
+  concise English release notes and the exact versioned IPK attachment.
+- Verify the published attachment's size and SHA-256 against the built IPK.
+- Reuse an existing release for the same version instead of creating a duplicate.
+- Never commit credentials or API tokens. SSH Git access alone does not grant
+  access to release creation or attachment upload; use an authorized web session
+  or an appropriately scoped existing API credential.
+
+The user has requested release publication as part of each future version.
+No additional publication confirmation is needed within that scope.