fix(proxy): emit fully-qualified parent for classes extending global classes

[lisachenko]

What and why

Fixes #759.

The bug: a woven class in a namespace that extends a global class, for example class Coll extends \ArrayObject in namespace Bug2, got extends ArrayObject in its proxy. That resolved to Bug2\ArrayObject, and including the proxy failed with Error: Class "Bug2\ArrayObject" not found.

The change:

• Parent class: ClassProxyGenerator roots the parent class name it takes from reflection: '\\' . $parentClass->getName(). This mirrors what was already done for the original interfaces.
• Introduced traits and interfaces: also always rooted, through a new rootClassName() helper. Callers that skip AdviceMatcher (which already roots them) are now safe too.
• Trait aliases: ClassGenerator::addTraitAlias() keeps the trait name as given instead of stripping the leading \. Before, an aliased global trait was written as GlobalTrait::m in the alias line, which resolved inside the proxy's namespace.
• What stays the same: ClassGenerator::classNameNode() keeps its semantics (only its docblock is extended). The FooOriginalTrait reference keeps its deliberate short relative name, and the short use aliases for framework and aspect classes are unchanged.
• Docs: one line in src/Proxy/AGENTS.md.

Verification

The repro from #759 (Bug2\Coll extends \ArrayObject with an advised hello(), empty cache):

	before	after
Output	Fatal error: Uncaught Error: Class "Bug2\ArrayObject" not found	[advice] coll
Proxy declaration	class Coll extends ArrayObject implements \IteratorAggregate, …	class Coll extends \ArrayObject implements \IteratorAggregate, …

Tests

• Snapshots: new fixture global-parent-class.php (Test\ns1\GlobalParentCollection extends \ArrayObject implements \Countable) with woven and proxy snapshots. WeavingTransformerTest::testWeaverRootsGlobalParentClassOfNamespacedClass compares against them and asserts the proxy compiles.
• Runtime load: testWovenClassWithGlobalParentClassWorksAtRuntime includes the woven trait and proxy from vfs, then checks is_subclass_of(\ArrayObject), instantiation and item access.
• ClassProxyGeneratorTest:
  • a global parent is emitted as extends \ArrayObject, while the OriginalTrait use stays short;
  • introduced global traits and interfaces are rooted, whether they are passed with or without a leading \.
• ClassGeneratorTest: the alias of an explicitly rooted global trait stays fully qualified.
• Existing snapshots: none changed.
• Gates, run locally: full phpunit (3095 tests), phpstan level 10 and php-cs-fixer are green. Only src/Proxy is touched, so the transformation performance group does not apply.

No CHANGELOG entry: the bug comes from the trait-based engine of the unreleased 4.0.

Checklist

• The title follows Conventional Commits (type(scope): summary)
• Tests cover the change
• composer check passes
• User-facing or breaking changes are in CHANGELOG.md (and the upgrade guide for breaking changes)

🤖 Generated with Claude Code

https://claude.ai/code/session_01KXjD75egSqDNujmNS5kr5c

---

Generated by Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.64%. Comparing base (4e95fdd) to head (1110746).

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #762   +/-   ##
=========================================
  Coverage     97.63%   97.64%           
- Complexity     1829     1830    +1     
=========================================
  Files           104      104           
  Lines          4829     4831    +2     
=========================================
+ Hits           4715     4717    +2     
  Misses          114      114           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.