Add processor and pass-graph conformance test suites

[Super-Genius]

Problem

The SGProcessingManager build does not register a test subdirectory or test targets in its root CMake configuration, and code search found no processor/pass execution test suite. The planned changes to pass dispatch, named bindings, graph execution, Vulkan rendering, cancellation, and structured results need one common contract to prevent backend-specific drift.

Scope

Add unit, integration, and conformance tests for the SGProcessingManager public execution contract.

Test areas:

• Schema parsing and pass-specific validation.
• Pass/input indexing and optional-field safety.
• Named multi-input, multi-output, and intermediate bindings.
• Linear, branching, merging, disabled, invalid, and cyclic pass graphs.
• Executor selection by pass type and backend.
• Existing MNN processors, including current LLM/FP4 work when merged.
• Existing SuperGenius Vulkan compute and render integration, including the existing MoltenVK path.
• Output hashing, artifact metadata, persistence, and deterministic serialization.
• Cancellation, deadline, budget, progress, partial result, and cleanup behavior.
• Capability acceptance and rejection cases.
• Backward compatibility adapters during interface migration.

Tests should use small deterministic fixtures and avoid downloading large public models during normal CI.

Acceptance criteria

• CTest targets run from the standalone SGProcessingManager build and when consumed by SuperGenius/develop.
• Each registered executor runs the same core conformance contract.
• Native Vulkan and the existing MoltenVK path run equivalent compute/render fixtures where CI hardware permits; unsupported CI environments skip with an explicit reason.
• Regression tests cover the concrete index mismatch, model-only assumption, output-buffer-zero fallback, and unsupported pass fallthrough bugs.

Tracks issues #7 through #14.

Base implementation and review work on the branch consumed by SuperGenius/develop.