Fix OptiScaler NGX routing and align marker polling defaults

- Explicitly route OptiScaler to d4r\nvngx.dll in release packages.

- Extract INI generation into a helper that preserves line endings
  and rejects missing or duplicate settings.

- Check NGX routing separately from file presence and return failure
  when the installation is incomplete or misconfigured.

- Add an optional OptiScaler patch for external DLSS backends while
  preserving AMD identity for FSR4, with matching launch guidance.

- Align portable and launcher marker polling defaults at 200 us.

- Log when d4r's model override replaces game or OptiScaler presets.

- Add configuration, package, routing and coexistence regression tests.

- Update installation documentation, add FSR/DLSS comparison videos
  and ignore local .tools artifacts.

Refs: #7, #14

scripts/d4r_config.py

@@ -146,7 +146,7 @@ def main(argv):
         value = flag("Interop", key)
         if value is not None:
             env[var] = "1" if value else "0"
-    value = get("Interop", "MarkerPollUs")
+    value = get("Interop", "MarkerPollUs") or "200"
     dilation = get("Interop", "MotionVectorDilation")
     if dilation is not None and dilation not in ("0", "1", "2"):
         fail("[Interop] MotionVectorDilation must be 0, 1 or 2")