Add a script to easily compare failed snapshot tests (#8346)

### Related

- Related to #8182 

### What

Introduce a new helper to manage and visualise failed kittest snapshot
tests using Rerun.

```
pixi run snapshots --help

# view all failed snapshot
pixi run snapshots

# remove all failed snapshot temp files
pixi run snapshots --clean

# only view (or clean) snapshot for that crate
pixi run snapshots -p re_time_panel
```


https://github.com/user-attachments/assets/c2ad63be-ff85-4235-a161-a359ff540d89

pixi.toml

@@ -354,6 +354,8 @@ py-test = { cmd = "python -m pytest -vv rerun_py/tests/unit", depends-on = [
   "py-build",
 ] }
 
+snapshots = "python scripts/snapshots.py"
+
 [feature.python-docs.tasks]
 # Build the documentation search index.
 # See `pixi run search-index --help` for more information.

scripts/snapshots.py

@@ -0,0 +1,128 @@
+"""
+View or clean failed kittest snapshot tests.
+
+Usage:
+```
+pixi run snapshot --help
+```
+"""
+
+from __future__ import annotations
+
+import argparse
+from pathlib import Path
+from sys import stderr
+from typing import Iterator
+
+import numpy as np
+import PIL.Image as Image
+import rerun as rr
+import rerun.blueprint as rrb
+
+CRATES_DIR = Path(__file__).parent.parent / "crates"
+
+
+def find_failed_snapshot_tests(package: str | None) -> Iterator[tuple[Path, Path, Path]]:
+    for diff_path in CRATES_DIR.rglob("**/*.diff.png"):
+        if package is not None:
+            if not any(package == str(part) for part in diff_path.parts):
+                continue
+
+        original_path = diff_path.parent / diff_path.name.replace(".diff.png", ".png")
+        new_path = diff_path.parent / diff_path.name.replace(".diff.png", ".new.png")
+
+        if original_path.exists() and new_path.exists():
+            yield original_path, new_path, diff_path
+
+
+def blueprint(path: Path) -> rrb.Blueprint:
+    test_name = path.stem
+    crate_name = path.relative_to(CRATES_DIR).parts[1]
+
+    return rrb.Blueprint(
+        rrb.Tabs(
+            rrb.Horizontal(
+                rrb.Spatial2DView(origin="original", name="Original"),
+                rrb.Spatial2DView(origin="new", name="New"),
+                rrb.Spatial2DView(origin="diff", name="Diff"),
+                name="Side-by-side",
+            ),
+            rrb.Tabs(
+                rrb.Spatial2DView(origin="original", name="Original"),
+                rrb.Spatial2DView(origin="new", name="New"),
+                rrb.Spatial2DView(origin="diff", name="Diff"),
+            ),
+            rrb.Tabs(
+                rrb.Vertical(
+                    rrb.Spatial2DView(
+                        contents=["/original", "/new"],
+                        name="Overlay (opacity)",
+                        overrides={
+                            "/new": [rr.components.Opacity(0.5)],
+                        },
+                    ),
+                    name='NOTE: Select the "new" entity visualizer and play with the "Opacity" component',
+                ),
+                name="Overlay (tab)",
+            ),
+            name=f"{crate_name}/{test_name}",
+        ),
+        rrb.TimePanel(expanded=False),
+    )
+
+
+def log_failed_snapshot_tests(original_path: Path, new_path: Path, diff_path: Path, args: argparse.Namespace) -> None:
+    recording = rr.new_recording(f"rerun_example_{original_path.stem}")
+
+    with recording:
+        default_blueprint = blueprint(original_path)
+
+        if args.stdout:
+            rr.stdout(default_blueprint=default_blueprint)
+        elif args.serve:
+            rr.serve(default_blueprint=default_blueprint)
+        elif args.connect:
+            rr.connect(args.addr, default_blueprint=default_blueprint)
+        elif args.save is not None:
+            rr.save(args.save, default_blueprint=default_blueprint)
+        elif not args.headless:
+            rr.spawn(default_blueprint=default_blueprint)
+
+        rr.log("original", rr.Image(np.array(Image.open(original_path))), static=True)
+        rr.log("new", rr.Image(np.array(Image.open(new_path))), static=True)
+        rr.log("diff", rr.Image(np.array(Image.open(diff_path))), static=True)
+
+        rr.log(
+            "doc/tabs",
+            rr.TextDocument(
+                "### Click on one of the tabs below to show the Original/New/Diff images.", media_type="text/markdown"
+            ),
+        )
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Logs all failed snapshot tests for comparison in rerun")
+    parser.add_argument("-p", "--package", type=str, help="Only consider the provided package")
+    parser.add_argument("--clean", action="store_true", help="Clean snapshot files instead of displaying them")
+    rr.script_add_args(parser)
+
+    args = parser.parse_args()
+
+    none_found = True
+    for original_path, new_path, diff_path in find_failed_snapshot_tests(args.package):
+        none_found = False
+
+        if args.clean:
+            print(f"Removing {new_path}", file=stderr)
+            new_path.unlink(missing_ok=True)
+            print(f"Removing {diff_path}", file=stderr)
+            diff_path.unlink(missing_ok=True)
+        else:
+            log_failed_snapshot_tests(original_path, new_path, diff_path, args)
+
+    if none_found:
+        print("No failed snapshot found", file=stderr)
+
+
+if __name__ == "__main__":
+    main()