fix(weaving): write all proxies of a source file into one cache file

[lisachenko]

What and why

Fixes #760.

When one source file declares several woven class-likes, each proxy used to be written to the same cache path (derived from the source file), so the last one won: the earlier proxies were overwritten and their classes were "not found" at runtime.

Now all proxies of a file go into one proxy file, included once by the woven source:

• WeavingTransformer::processSingleClass() returns a WovenProxy instead of writing the file; transform() collects them locally (transform() is re-entered mid-transform, so no property state) and writeProxies() writes them through saveProxyToCache() and appends one include_once.
• Single proxy: output is byte-identical to master; include right after the class, no extra checks.
• Several proxies: declare(strict_types=1); once, then one braced namespace block per proxy (each keeps its own ProxyImports aliases, short use names preserved). A proxy extending another proxy of the same file is emitted after it.
• Include point (ProxyIncludePlanner): after the last woven class-like whose proxy is position-bound (its woven trait keeps trait uses, or it extends/implements an unwoven class-like of the file), otherwise after the first woven one.
• Load-order gap → WeavingException with file, woven classes, include point and each offending line: code running before the include point that needs a woven class-like of the file (new X, X::m(), X::$p, X::C, extends/implements/uses). Not flagged: X::class, instanceof, types, function/closure/arrow-function bodies (LoadedClassNameCollector).
• New @internal final classes: WovenProxy, ProxyIncludePlanner, LoadedClassNameCollector, Go\Proxy\ProxyFileGenerator. GeneratorInterface::getStmts() added (Class/Enum/TraitGenerator), ClassProxyGenerator::generateStmts(), GeneratedCodePrinter gets a bracedNamespaces option.
• No FORMAT_VERSION bump (next release is a major anyway).

Repro (from #760)

	Bug1\First	Bug1\Second
master	not found	✅
this PR	✅ [advice] first	✅ [advice] second

Performance (composer test:performance:transformation, base vs head alternating, 7 runs each, medians)

case	base ratio	head ratio	head/base
rewriter, default rules	0.0958	0.0979	1.02 (noise)
rewriter, all rules	1.3456	1.3401	1.00
WeavingTransformer	0.2424	0.2319	0.96

Tests

• Snapshots: multiple-classes/multiple-ns/php80-*attribute* woven files now have one include; new proxy snapshots for multiple-classes, multiple-ns, multiple-mixed (interface, unwoven class, enum, in-file parent, namespace {}) — compiled and loaded at runtime in vfs.
• Byte identity for single class / enum / class with static init vs master output.
• Parent-proxy ordering, static-init call stays in its namespace block, gap positive & negative cases.
• Functional MultiClassFileTest + ProductionMultiClassFileTest (production instantiates the third class first → runtime class map path).

Known limitations / follow-ups

• An unwoven same-file interface always makes a class position-bound (PHP would declare a parent-less interface at compile time), so the include may land later than strictly needed.
• Weaving a class whose parent is declared in the same file still requires the parent to be locatable by composer (parser-reflection locator) — same as master; the fixture registers it in the classmap.

Checklist

• The title follows Conventional Commits (type(scope): summary)
• Tests cover the change
• composer check passes (phpunit 3099 OK, phpstan level 10 clean, php-cs-fixer clean)
• 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

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Generated by Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.74%. Comparing base (4e95fdd) to head (cd84761).

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #764      +/-   ##
============================================
+ Coverage     97.63%   97.74%   +0.10%     
- Complexity     1829     1918      +89     
============================================
  Files           104      108       +4     
  Lines          4829     5012     +183     
============================================
+ Hits           4715     4899     +184     
+ Misses          114      113       -1     

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[lisachenko]

Very heavy implementation - too complex. Drop this and rethink with minimum changes - do not introduce a lot of new classes…