Add decompile runner workflow

.codex/project.md

@@ -0,0 +1,60 @@
+# Codex Project Notes
+
+## Project
+
+`Explosion Overhaul` is a private porting workspace for moving the upstream Forge 1.20.1 mod `Explosion Overhaul: A new level of destruction` to NeoForge `21.1.228` for Minecraft `1.21.1`.
+
+Repository:
+
+```text
+MrSphay/Explosion-Overhaul
+```
+
+## Commands
+
+Local Java is not available in the current Codex environment, so Java tasks should run on the Gitea runner until a local JDK is configured.
+
+Planned commands:
+
+```text
+./gradlew build
+./gradlew runClient
+```
+
+Windows equivalents:
+
+```text
+gradlew.bat build
+gradlew.bat runClient
+```
+
+## Stack
+
+Minecraft mod, Java 21, NeoForge `21.1.228`, Minecraft `1.21.1`.
+
+## Build Artifacts
+
+Release artifacts are produced in:
+
+```text
+build/libs
+```
+
+Expected files:
+
+```text
+explosionoverhaul-*.jar
+```
+
+## Security And License Rules
+
+- Treat the decompiled upstream source as private porting material.
+- Do not publish or redistribute the port without permission from the original author.
+- Keep tokens and registry credentials out of the repository.
+- External network calls currently used by runner workflows:
+  - Modrinth CDN for the upstream jar.
+  - CFR website for the decompiler jar.
+
+## Current Porting State
+
+The cloned repository initially contained the Codex Agent Repository Kit, not mod source. The first runner step is `.gitea/workflows/decompile.yml`, which creates a decompiled-source artifact for reconstruction.