Add imgrep utility to search for text in a set of files

This is useful for finding test cases in various images I have saved in my
`Downloads` directory that don't have useful filenames. It might make sense to
have this as a built-in feature of the ocrs tool in future. In the meantime
it is a useful test case of `ocrs` in a batch-processing pipeline.

tools/imgrep.py

@@ -0,0 +1,45 @@
+import argparse
+import subprocess
+import sys
+
+
+def find_images_with_text(files: list[str], text: str) -> list[str]:
+    """
+    Search for images in `files` containing the given text.
+
+    Returns a list of matching file paths.
+    """
+    allowed_extensions = (".png", ".jpg", ".jpeg", ".webp")
+    paths = []
+    files = [fname for fname in files if fname.lower().endswith(allowed_extensions)]
+
+    for i, filename in enumerate(files):
+        print(f"\rReading image {i+1}/{len(files)}...", end="", file=sys.stderr)
+
+        try:
+            result = subprocess.run(
+                ["ocrs", filename], capture_output=True, text=True, check=True
+            )
+            if text.lower() in result.stdout.lower():
+                paths.append(filename)
+        except subprocess.CalledProcessError as e:
+            print(f"Error processing {filename}: {e}", file=sys.stderr)
+
+    # Add new line after progress message
+    print("", file=sys.stderr)
+
+    return paths
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="Search for text in images")
+    parser.add_argument(
+        "files", help="Files to search. Non-image files are ignored.", nargs="*"
+    )
+    parser.add_argument("text", help="Text to search for")
+
+    args = parser.parse_args()
+
+    paths = find_images_with_text(args.files, args.text)
+    for path in paths:
+        print(path)