fix(path): preserve path casing on case-sensitive filesystems (#48)

toSimplePath() unconditionally lowercased all paths, which corrupted
paths on case-sensitive filesystems (Linux, case-sensitive macOS APFS).
Git operations would fail because the lowercased cwd did not exist,
causing the "Please open at least one Git repository in workspace" error.

Only apply toLowerCase() on Windows where the filesystem is
case-insensitive. The backslash normalization remains unconditional.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Samuel-Harris

src/core/util/path.ts

@@ -1,7 +1,8 @@
 import path from 'path';
 
 function toSimplePath(path: string) {
-    return path.toLowerCase().replace(/\\/g, '/');
+    const normalized = path.replace(/\\/g, '/');
+    return process.platform === 'win32' ? normalized.toLowerCase() : normalized;
 }
 
 function comparePath(path1: string = '', path2: string = '') {