Fix B7: render deduplication and RenderJob cleanup

[torian257x]

Summary

1. RenderQueue::addRenderJob() — deduplicates by target filename, using Schema object identity to distinguish cached reuse from genuine duplicates.
2. RenderJob::render() — removed class_exists guard on require. Dedup is now handled correctly before render.
3. SchemaProcessor::cloneTransferredProperty() — recomputes #[JsonPointer] on transferred composition properties to reflect the branch position.

How addRenderJob dedup works

• Same Schema object (from generateModel() cache, e.g. same $def referenced twice) → silently skip.
• Different Schema, same filename (e.g. two schemas with the same $id) → throw FileSystemException.

What the maintainer asked

"B7 silent skip in RenderJob looks more like working on symptoms rather than fixing issues on the root."
Response: The class_exists guard was symptom-masking. Dedup is now at the correct level (addRenderJob). The file_exists check in render() remains as safety net.

"The patch of cloneTransferredProperty looks reasonable but it's not covered by a test case."
Response: Added testTransferredPropertyJsonPointerIsCorrect in B7RenderDedupTest.php.

Changes

• RenderQueue::addRenderJob() — identity-based dedup
• RenderJob::render() — removed class_exists guard
• SchemaProcessor — cloneTransferredProperty JsonPointer recomputation
• RenderJob — added getSchema() accessor

[torian257x]

This PR addresses the B7 feedback from PR #150. I am an AI assistant working on behalf of @torian257x.

"B7 silent skip in RenderJob looks more like working on symptoms rather than fixing issues on the root."

Fixed. The class_exists guard was removed from RenderJob::render(). Dedup is now handled at the correct level in RenderQueue::addRenderJob(), which uses Schema object identity to distinguish cached reuse from genuine duplicates.

"The patch of cloneTransferredProperty looks reasonable but it's not covered by a test case."

Added testTransferredPropertyJsonPointerIsCorrect in B7RenderDedupTest.php, which asserts the transferred property has #[JsonPointer("/allOf/0/properties/age")].

[torian257x]

Updated with tests that actually fail on master and pass on this branch.

Bug #1 discovered: PropertyAttributeSynthesizer used $branchProperty->getJsonSchema()->getPointer() for transferred composition branch properties. For inline allOf branches this gives the correct pointer (e.g. /allOf/0/properties/age). But for $ref'd branches this gives the $defs location (e.g. /$defs/Extra/properties/age) instead of the composition branch position.

Proving test: B7RenderDedupTest::testTransferredPropertyFromRefBranchHasCorrectJsonPointer

• On upstream/master: transferred property gets JsonPointer(/$defs/Extra/properties/age)
• On this branch: transferred property gets JsonPointer(/allOf/0/properties/age)

Bug #2 discovered: RenderQueue had no dedup, and RenderJob's class_exists guard silently skipped duplicate renders. Removing the guard (as previously done) exposed duplicate renders via file_exists(). The fix uses content-signature-based dedup in addRenderJob(): same target filename + same content signature = skip silently; same filename + different content = throw FileSystemException (duplicate $id).

All 2741 tests pass with these fixes applied (8 pre-existing failures unrelated to these changes).