fix(test): make CwdDrift revert-hint assertion platform-agnostic

InvokeExpression_CwdDriftNotice_EscapesSingleQuotesInRevertHint asserted
the literal substring "Set-Location -LiteralPath ''C:" in the bail
response. That worked on Windows where Path.GetTempPath() returns a
C:\... path, but on Linux (/tmp/...) and macOS (/var/folders/...) the
"C:" prefix never appeared, so the test was failing in CI on both
non-Windows runners while staying green locally.

The intent of the assertion is to confirm the apostrophe-doubling
escape (' -> '') gets applied to the AI''s intended cwd before it
reaches the AI as part of a single-quoted PowerShell literal. Build
the expected substring from aiCwd itself (with the same Replace
applied) so the test exercises the escape contract on every platform
without baking in a path prefix.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: yotsuda

Tests/Unit/Proxy/PowerShellToolsTests.cs

@@ -1189,9 +1189,14 @@ public async Task InvokeExpression_CwdDriftNotice_EscapesSingleQuotesInRevertHin
             "Get-Date",
             agent_id: TestAgentId);
 
-        // Assert: apostrophe doubled inside the literal-path argument
+        // Assert: apostrophe doubled inside the literal-path argument.
+        // Build the expected substring from aiCwd itself so the test passes on every
+        // platform — Path.GetTempPath() returns /tmp/... on Linux and /var/folders/...
+        // on macOS, neither of which starts with "C:". The escape rule (' -> '') is
+        // what we actually want to lock in.
+        var expectedRevertHint = $"Set-Location -LiteralPath '{aiCwd.Replace("'", "''")}'";
         Assert.Contains("Pipeline NOT executed", result);
-        Assert.Contains("Set-Location -LiteralPath 'C:", result);
+        Assert.Contains(expectedRevertHint, result);
         Assert.Contains("o''brien", result);
 
         // Cleanup