update bug report template: add diagnostics instructions and Windows field

.github/ISSUE_TEMPLATE/bug_report.md

@@ -18,12 +18,18 @@ Steps to reproduce the behaviour:
 **Expected behaviour**
 What you expected to happen.
 
+**Diagnostics**
+Open the app → Settings → Diagnostics, then click "Copy All" and paste the output here.
+This shows the exact error, org ID, and cookie state without exposing sensitive data.
+
 **Screenshots**
 If applicable, add screenshots to help explain your problem.
 
 **Environment**
-- macOS version: [e.g. Sequoia 15.4]
-- ClaudeChecker version: [e.g. 1.1.3]
+- Platform: [macOS / Windows]
+- macOS version: [e.g. Sequoia 15.4] *(if applicable)*
+- Windows version: [e.g. Windows 11 24H2] *(if applicable)*
+- ClaudeChecker version: [e.g. 1.3.2]
 - Claude plan: [e.g. Pro, Max]
 
 **Additional context**