fix: indent Python heredoc content to satisfy YAML block scalar rules

Python script lines at column 0 inside a run: | block scalar caused
the YAML parser to treat them as ending the block, making the entire
workflow file unparseable — so the action never ran at all.

YAML block scalars require every content line to be indented at least
as deep as the block's own indentation (10 spaces here). GitHub Actions
strips that minimum indentation before passing the script to bash, so
the heredoc writes the Python file with correct zero-based indentation.

https://claude.ai/code/session_01Lg4VQQXs3q3WW4aMoe3Xci

Author: claude

.github/workflows/screenshot.yml

@@ -235,17 +235,17 @@ jobs:
           # Write Python helper with single-quoted heredoc (no shell substitution),
           # then pass variables as argv so there are no quoting/expansion issues.
           cat > /tmp/make_body.py << 'PYEOF'
-import json, base64, sys
-img_path, commit_msg, existing_sha = sys.argv[1], sys.argv[2], sys.argv[3]
-with open(img_path, "rb") as f:
-    content = base64.b64encode(f.read()).decode()
-body = {"message": commit_msg, "content": content, "branch": "screenshots"}
-if existing_sha:
-    body["sha"] = existing_sha
-with open("/tmp/upload-body.json", "w") as f:
-    json.dump(body, f)
-print(f"Upload body: {len(content)} base64 chars")
-PYEOF
+          import json, base64, sys
+          img_path, commit_msg, existing_sha = sys.argv[1], sys.argv[2], sys.argv[3]
+          with open(img_path, "rb") as f:
+              content = base64.b64encode(f.read()).decode()
+          body = {"message": commit_msg, "content": content, "branch": "screenshots"}
+          if existing_sha:
+              body["sha"] = existing_sha
+          with open("/tmp/upload-body.json", "w") as f:
+              json.dump(body, f)
+          print(f"Upload body: {len(content)} base64 chars")
+          PYEOF
           python3 /tmp/make_body.py "/tmp/mc-screenshot.png" "$COMMIT_MSG" "$EXISTING_SHA" \
             || { echo "WARNING: failed to build upload body"; exit 0; }