Fix/openclaude diagnostics settings (#483)

* fix: use openclaude paths in diagnostics and settings

* fix: strip leaked reasoning from assistant output

* fix: preserve legacy claude config compatibility

* fix: tighten path and reasoning compatibility

* fix: buffer streamed reasoning leak preambles

* test: cover openclaude migration and reasoning fixes

* test: isolate execFileNoThrow from cross-file mocks

src/ink/termio/osc.test.ts

@@ -13,6 +13,7 @@ const execFileNoThrowMock = mock(
 
 mock.module('../../utils/execFileNoThrow.js', () => ({
   execFileNoThrow: execFileNoThrowMock,
+  execFileNoThrowWithCwd: execFileNoThrowMock,
 }))
 
 mock.module('../../utils/tempfile.js', () => ({