fix(symfony,laravel): IriConverter local cache key collision between item and collection ops

[soyuka]

Summary

The IriConverter::$localOperationCache key in both the Symfony and Laravel routing converters used a suffix scheme that collided for legitimately distinct call patterns. Under worker runtimes (FrankenPHP, Swoole, Octane) the converter survives across requests, so the collision corrupts IRI generation for any subsequent request that lands on the leaked slot.

Symfony (src/Symfony/Routing/IriConverter.php): _c was shared by is_string(\$resource) AND \$operation instanceof CollectionOperationInterface. After a POST that triggers PurgeHttpCacheListener::postFlush, a GetCollection operation is cached under '' . Class . '_c'. Any later call like getIriFromResource(Class::class, ABS_PATH, new Get(), ['uri_variables' => ['id' => 1]]) hits the same slot and gets the cached GetCollection — producing /things?id=1 instead of /things/1. AbstractItemNormalizer::getResourceFromIri then throws Invalid IRI.

Laravel (src/Laravel/Routing/IriConverter.php): broader scope — the key didn't check CollectionOperationInterface at all, so any string-resource call shared one slot regardless of operation type. PurgeHttpCacheListener already primes that slot with a GetCollection on every save/delete (see src/Laravel/Eloquent/Listener/PurgeHttpCacheListener.php:50).

Fix

Both converters now encode the two axes independently in the cache suffix:

• _s / _o — string vs object resource
• _c / _i — collection vs item operation

Yielding four distinct slots (_s_c, _s_i, _o_c, _o_i) with no overlap.

Test plan

• tests/Functional/Json/RelationTest::testCreateRelatedDummyWithPlainIdentifierForRelation — end-to-end Symfony repro using RelatedDummyPlainIdentifierDenormalizer; sequential POST /third_levels then POST /related_dummies in the same kernel (\$alwaysBootKernel = false). Fails on 4.3 without the fix with Invalid IRI "/third_levels?id=1".
• src/Laravel/Tests/Unit/Routing/IriConverterTest::testLocalCacheKeyDistinguishesItemAndCollectionForStringResource — unit-level repro: anonymous new GetCollection() then anonymous new Get() for the same class-string. Fails on 4.3 without the fix (returns /api/books instead of /api/books/1).
• tests/Symfony/Routing/IriConverterTest (14 tests) and the broader tests/Symfony/Routing/ + tests/Functional/ run (691 tests) stay green.
• Laravel PurgerTest failures pre-exist on 4.3 and are unrelated to this change (verified by stashing the fix).