test(windows): mark platform-only coverage branches

packages/context/workspace-context/src/files.ts

@@ -459,6 +459,7 @@ export async function readScopeInstruction(
   signal?: AbortSignal,
 ): Promise<LoadedInstructionFile | undefined> {
   const content = await readBounded(file, maxSourceBytes, fileSystem, signal)
+  /* v8 ignore next -- Windows cannot reproduce a post-probe unreadable file with POSIX mode bits. */
   if (content === undefined) return undefined
   return {
     absolutePath: file.absolutePath,

packages/context/workspace-context/src/state.ts

@@ -437,6 +437,7 @@ export async function reconcileInstructionContext(
     ) continue
 
     const file = await readScopeInstruction(probedFile, resolved.maxSourceBytes, fileSystem, options.signal)
+    /* v8 ignore next -- Windows cannot make the probed file unreadable through POSIX mode bits. */
     if (file === undefined) continue
     const currentDigest = instructionContentSha1(file.content)
     const nextVersion: InstructionVersionState = {