fix: patched Kimi model edit mode fallback

- Added a fallback from `hashline` to `replace` mode for Kimi-family models to resolve compatibility issues.
- Introduced `PI_STRICT_EDIT_MODE` environment variable to bypass automatic model-specific edit-mode fallbacks.
- Updated `getEditVariantForModel` to perform case-insensitive matching for model variant configurations.
- Added comprehensive unit tests for edit mode resolution and settings configuration.

scripts/edit-benchmark.py

@@ -58,7 +58,7 @@ def build_spec(variant: str) -> BenchmarkSpec:
 		description=f"Benchmark edit tool in {variant} mode across models with simple edit tasks.",
 		workspace_prefix=f"{variant}-benchmark",
 		tools=("edit", "read"),
-		env={"PI_EDIT_VARIANT": variant},
+		env={"PI_EDIT_VARIANT": variant, "PI_STRICT_EDIT_MODE": "1"},
 		initial_prompt=prompt,
 		retry_instruction=retry,
 	)