u917 mark safeWriteText as an internal direct-test seam

Knip 5.88 counts the export as unused production API because no production file calls it yet. The repository's own quality-checks document, docs/development-quality-checks.md line 36, tells an author in this position to declare the seam with @internal and its reason next to the export rather than in configuration, and scripts/knip-policy.test.mjs asserts that case. Six comment lines, the export line untouched, no change to any configuration file and no suppression added.

Author: LiangE

src/services/file-safety/safeWriteText.ts

@@ -263,6 +263,12 @@ export async function resolveLockKey(absoluteFilePath: string): Promise<string>
 	}
 }
 
+/**
+ * @internal Intentional direct-test seam: no production file calls this write path
+ * yet, and this unit's own specs exercise it directly, which is the case
+ * `docs/development-quality-checks.md` line 36 tells authors to declare here rather
+ * than in configuration. Knip still follows the test imports in default mode.
+ */
 export async function safeWriteText(
 	filePath: string,
 	content: string | Uint8Array,