spark: add verified SHA256 hash utility tool with test verification

wizard-work/spark/VERIFICATION.txt

@@ -0,0 +1,19 @@
+VERIFICATION TEST: SHA256 TOOL
+================================
+
+Test 1: /etc/hostname
+Expected:  1c7ae0f30a68699c38441fd54bfbe20aed8e0c7c8793e25db41d2ff169b9639c
+Tool Output: 1c7ae0f30a68699c38441fd54bfbe20aed8e0c7c8793e25db41d2ff169b9639c
+Match: YES
+
+Test 2: /etc/passwd
+Expected:  24a9d154e8b4556887f514b99bcd92c4d15fefbf284ff7ad481dad412849bd24
+Tool Output: 24a9d154e8b4556887f514b99bcd92c4d15fefbf284ff7ad481dad412849bd24
+Match: YES
+
+Test 3: Error handling for missing file
+Expected: exit code 1, error message printed
+Result: exit_code=1, "Error: /nonexistent not found" printed
+Match: YES
+
+CONCLUSION: Tool verified correct against system sha256sum utility.

wizard-work/spark/sha256_tool.py

@@ -0,0 +1,25 @@
+#!/usr/bin/env python3
+"""SHA256 file hash calculator - quick utility for integrity verification."""
+import hashlib
+import sys
+from pathlib import Path
+
+def calc_sha256(file_path: str) -> str:
+    """Calculate SHA256 hash of a file."""
+    h = hashlib.sha256()
+    with open(file_path, 'rb') as f:
+        for chunk in iter(lambda: f.read(8192), b''):
+            h.update(chunk)
+    return h.hexdigest()
+
+if __name__ == '__main__':
+    if len(sys.argv) < 2:
+        print("Usage: sha256_tool.py <file>", file=sys.stderr)
+        sys.exit(1)
+    
+    path = Path(sys.argv[1])
+    if not path.exists():
+        print(f"Error: {path} not found", file=sys.stderr)
+        sys.exit(1)
+    
+    print(calc_sha256(str(path)))