fix(ci): release v1.6.1 — skip chmod tests when running as root

Four tests relied on os.Chmod to force error paths but were failing in
Docker CI (golang:1.26-alpine runs as root, where chmod restrictions have
no effect). Added os.Getuid() == 0 skip guards to:
- internal/gradle: TestWriteVersionReadOnly
- internal/gitutil: TestLatestTagTagsIterFails (replaced broken skip logic
  that only fired if Chmod itself errored)
- cmd: TestInitConfigWriteFails, TestRunLatestTagFails

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -3,6 +3,12 @@
 All notable changes to this project will be documented in this file.
 Format: [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
+## [1.6.1] - 2026-07-11
+
+### Fixed
+
+- **CI root-permission failures** — four tests that used `os.Chmod` to force error paths were failing in Docker CI (which runs as root, where chmod has no enforcement effect); each now skips with `os.Getuid() == 0`; the gitutil test had broken skip logic that only fired if `Chmod` itself errored — replaced with the same upfront UID check
+
 ## [1.6.0] - 2026-07-11
 
 ### Added

README.md

@@ -1,6 +1,6 @@
 # releaser
 
-![release](https://img.shields.io/badge/release-v1.6.0-blue.svg)
+![release](https://img.shields.io/badge/release-v1.6.1-blue.svg)
 
 A CI-friendly release automation tool for GitFlow workflows using Conventional Commits.