chore(release): bump version to 0.13.1 (#173)

- Fix submodule detection bug (listSubmodules failing on first submodule)
- Add gitExecRaw() function for raw stdout preservation
- Add comprehensive submodule tests
- Improve test coverage (submodule.ts: 79.78% → 93.53%)

🖥️ IDE: [Cursor](https://cursor.sh)
🔌 Extension: [Claude Code](https://claude.ai/download)


Model-Raw: claude-opus-4-5-20251101

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: nullvariant

extensions/git-id-switcher/CHANGELOG.md

@@ -7,6 +7,27 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.13.1] - 2026-01-18
+
+### Fixed
+
+- **Submodule Detection Bug**: Fixed `listSubmodules()` failing to detect the first submodule
+  - Root cause: `gitExec()` applied `stdout.trim()` which removed the leading status character
+  - Added `gitExecRaw()` function that preserves raw stdout without trimming
+  - `git submodule status` output format requires leading character (` `, `-`, `+`) for status
+
+### Added
+
+- **Comprehensive Submodule Tests**: Added tests for submodule detection scenarios
+  - Single submodule detection test
+  - Multiple submodules detection test (3 submodules)
+  - Nested submodules recursive test (3-level hierarchy)
+  - `gitExecRaw()` error handling test
+
+### Changed
+
+- **Improved Test Coverage**: `submodule.ts` coverage increased from 79.78% to 93.53%
+
 ## [0.13.0] - 2026-01-17
 
 ### Security

extensions/git-id-switcher/package.json

@@ -2,7 +2,7 @@
   "name": "git-id-switcher",
   "displayName": "%extension.displayName%",
   "description": "%extension.description%",
-  "version": "0.13.0",
+  "version": "0.13.1",
   "publisher": "nullvariant",
   "icon": "images/icon.png",
   "engines": {