pkg/aflow: add the Format action for repro.go

[ramosian-glider]

---

Before sending a pull request, please review Contribution Guidelines:
https://github.com/google/syzkaller/blob/master/docs/contributing.md

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[ramosian-glider]

@dvyukov there's a concurrent suggestion by @tarasmadan to rename the parameters globally before running the actions.

[ramosian-glider]

PTAL

I also have the following diff to GEMINI.md, I can include it here:

diff --git a/pkg/aflow/GEMINI.md b/pkg/aflow/GEMINI.md
index 73808137c..df4fde530 100644
--- a/pkg/aflow/GEMINI.md
+++ b/pkg/aflow/GEMINI.md
@@ -36,6 +36,21 @@ typically through the `syz-env` wrapper.
 
 ## Development Conventions
 
+### State Variable Naming Conventions
+
+To allow actions and workflows to be composed without complex renaming logic, we attach **semantic meaning** to state variable names rather than just using raw types.
+
+We globally agree on the semantics of names so that actions can work securely across any context:
+
+- **`BugTitle`**: The original bug title straight from the dashboard.
+- **`ReproducedBugTitle`**: The bug title that resulted from successfully running a reproducer.
+- **`CrashReport`**: The verbatim bug report body to reproduce.
+- **`CandidateReproSyz`**: A raw, unformatted syzkaller program typically generated directly by the LLM.
+- **`ReproSyz`**: A definitively formatted, verified, and ready-to-execute syzkaller program (e.g. the output of the `Format` action).
+- **`ReproOpts`**: Reproducer configuration options.
+- **`KernelRepo` / `KernelBranch` / `KernelCommit`**: Information uniquely identifying the target kernel tree and revision.
+- **`KernelConfig`**: The kernel build setup configuration.
+
 ### Defining Workflows
 
 Workflows are typically registered using `aflow.Register`.

[dvyukov]

I also have the following diff to GEMINI.md, I can include it here:

whichever you prefer