fix: improve global self-update scope detection

[coisa]

Related Issue

Closes #335

Motivation / Context

dev-tools self-update was still behaving as local in certain environments (symlinked/alternate Composer home paths), so global updates could route through local project contexts.

The branch introduces a more robust Composer scope detection flow for self-update, including:

• safer composer-home path normalization (with realpath/canonicalization fallback),
• recognition of XDG_CONFIG_HOME/composer as a valid Composer home candidate, and
• stronger candidate matching logic before deciding local vs global scope.

Changes

• Restore/extend self-update home-path canonicalization in ComposerSelfUpdateScopeResolver.
• Add Composer XDG_CONFIG_HOME as an additional resolution candidate for global composer home detection.
• Added/updated unit coverage in ComposerSelfUpdateScopeResolverTest for the new candidate path.

Verification

• composer dev-tools via commit-time hook
• Focused command(s): pre-commit validation ran during commit
• Manual verification: reproducible global-vs-local scope behavior should be revalidated with symlinked/alternate composer home flows

Documentation / Generated Output

• README updated
• docs/ updated
• Generated or synchronized output reviewed

Changelog

• Added a notable CHANGELOG.md entry

Reviewer Notes

This is the intermediate self-update fix requested before full git-hooks externalization; the issue-specific change is intentionally scoped.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 1b54c269-6239-4de0-8965-3aeb73688148

📥 Commits

Reviewing files that changed from the base of the PR and between 18d1cf4 and 1a3bef2.

📒 Files selected for processing (4)

• .github/wiki
• CHANGELOG.md
• src/SelfUpdate/ComposerSelfUpdateScopeResolver.php
• tests/SelfUpdate/ComposerSelfUpdateScopeResolverTest.php

---

📝 Walkthrough

Summary by CodeRabbit

• Bug Fixes
  • Improved self-update global/local scope detection to correctly handle symlinked Composer home environments and added support for XDG_CONFIG_HOME, preventing unintended global installs from being treated as local updates.
• Tests
  • Added tests covering Composer home detection including XDG_CONFIG_HOME scenarios.
• Documentation
  • Updated changelog noting the fix and scope-detection improvements.

Walkthrough

The PR hardens global installation detection in ComposerSelfUpdateScopeResolver by introducing path normalization with symlink resolution and adding XDG_CONFIG_HOME support for Composer home discovery. A wiki submodule reference is also updated.

Changes

Global Installation Detection with XDG Support

Layer / File(s)	Summary
Path normalization helper src/SelfUpdate/ComposerSelfUpdateScopeResolver.php	New normalizePath() method resolves symlinks via realpath() with fallback to direct canonicalization when resolution fails; imports updated to support safe realpath usage.
Composer home candidate discovery src/SelfUpdate/ComposerSelfUpdateScopeResolver.php	getComposerHomeCandidates() adds XDG_CONFIG_HOME/composer as a candidate path alongside existing COMPOSER_HOME, HOME, macOS, and APPDATA variants.
Global installation detection src/SelfUpdate/ComposerSelfUpdateScopeResolver.php	isGlobalInstallation() now uses normalized paths for comparisons, enabling robust detection in setups with symlinked Composer homes.
Test coverage and validation tests/SelfUpdate/ComposerSelfUpdateScopeResolverTest.php	Existing test cases explicitly mock XDG_CONFIG_HOME as null; new test verifies isGlobalInstallation() returns true when package is under an XDG_CONFIG_HOME-derived Composer home.
Changelog documentation CHANGELOG.md	Documents improved self-update global/local scope detection with realpath fallback and XDG_CONFIG_HOME support.

Submodule Reference Update

Layer / File(s)	Summary
Wiki submodule commit update .github/wiki	The .github/wiki git subproject reference is updated to a newer commit.

🎯 2 (Simple) | ⏱️ ~12 minutes

🐰 Paths unwound from their tangled links,
XDG homes found in symlink shrinks,
A global detection gets quite shrewd—
No more confusion from forked nodes!
Hops of code now find their rightful paths.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/336-self-update-global-scope

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[github-actions]

🚀 Preview is available for this pull request.

• Docs: https://php-fast-forward.github.io/dev-tools/previews/pr-337/
• Coverage: https://php-fast-forward.github.io/dev-tools/previews/pr-337/coverage/
• Metrics: https://php-fast-forward.github.io/dev-tools/previews/pr-337/metrics/