feat: Add new Geometry Nodes groups for image relief and shadeless shader

- Implemented the "O Image Relief Plane" Geometry Nodes group to create a fixed-base image relief using depth images and various parameters.
- Created the "O Shadeless" shader node group to display color without scene lighting while preserving shadows and reflections.
- Introduced a preview feature for node groups, allowing for interactive visualization of node arrangements in an HTML format.
- Added a template HTML file for rendering node previews with customizable views and controls.

tools/nodes/cli.py

@@ -0,0 +1,101 @@
+import argparse
+import os
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+from tempfile import TemporaryDirectory
+from zipfile import ZipFile
+
+
+PROJECT_ROOT = Path(__file__).resolve().parents[2]
+BLENDER_MODULES = (
+    "tools.nodes.build",
+    "tools.nodes.check",
+)
+
+
+def project_env_value(name, path=None):
+    env_path = path or PROJECT_ROOT / ".env"
+    if not env_path.is_file():
+        return None
+    for raw_line in env_path.read_text(encoding="utf-8").splitlines():
+        line = raw_line.strip()
+        if not line or line.startswith("#"):
+            continue
+        if line.startswith("export "):
+            line = line.removeprefix("export ").lstrip()
+        key, separator, value = line.partition("=")
+        if separator and key.strip() == name:
+            value = value.strip()
+            if len(value) >= 2 and value[0] == value[-1] and value[0] in "\"'":
+                value = value[1:-1]
+            return value or None
+    return None
+
+
+def blender_path(explicit=None):
+    candidate = (
+        explicit
+        or os.environ.get("BLENDER_BIN")
+        or project_env_value("BLENDER_BIN")
+        or shutil.which("blender")
+    )
+    if not candidate:
+        raise RuntimeError(
+            "Blender not found: pass --blender, set BLENDER_BIN, add it to .env, "
+            "or add blender to PATH"
+        )
+    path = Path(candidate).expanduser()
+    if not path.is_file():
+        raise RuntimeError(f"Blender executable does not exist: {path}")
+    return path
+
+
+def run(command):
+    print("+", subprocess.list2cmdline([str(part) for part in command]), flush=True)
+    subprocess.run(command, cwd=PROJECT_ROOT, check=True)
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="Build and validate O_AnyImage.blend.",
+    )
+    parser.add_argument(
+        "--blender",
+        help="Blender executable; overrides BLENDER_BIN, .env, and PATH.",
+    )
+    parser.add_argument(
+        "--skip-tests",
+        action="store_true",
+        help="Skip the Python test suite.",
+    )
+    options = parser.parse_args()
+    executable = blender_path(options.blender)
+
+    with TemporaryDirectory(prefix="anyimage-node-dependencies-") as directory:
+        for wheel in (PROJECT_ROOT / "src" / "anyimage" / "wheels").glob("scipy-*.whl"):
+            with ZipFile(wheel) as archive:
+                archive.extractall(Path(directory) / wheel.name.split("-")[2])
+        paths = [str(PROJECT_ROOT), str(PROJECT_ROOT / "src"),
+                 str(next((PROJECT_ROOT / "src/anyimage/wheels").glob("blendjob-*.whl")))]
+        bootstrap = (
+            f"import sys, runpy; sys.path[:0] = {paths!r}; "
+            f"sys.path.insert(0, {directory!r} + '/cp' + str(sys.version_info.major) + str(sys.version_info.minor)); "
+        )
+        for module_name in BLENDER_MODULES:
+            run(
+                (
+                    executable,
+                    "--factory-startup",
+                    "--background",
+                    "--python-exit-code", "1",
+                    "--python-expr", bootstrap + f"runpy.run_module({module_name!r}, run_name='__main__')",
+                )
+            )
+    if not options.skip_tests:
+        run((sys.executable, "-m", "pytest"))
+
+
+if __name__ == "__main__":
+    main()