Add StableHLO export contract and IREE CPU compile baseline

[michalharakal]

Add StableHLO export contract and IREE CPU compile baseline

SKaiNET already lowers its Kotlin DSL to MLIR StableHLO and produces “valid IREE-compilable output,” while IREE documents StableHLO as an accepted input format and provides a standard CPU path through iree-compile, iree-run-module, and the llvm-cpu backend. This milestone makes that claim testable with a narrow, repeatable contract on CPU first.
Background links:

• SKaiNET README and compiler overview. ([GitHub][1])
• SKaiNET HLO getting started. ([GitHub][2])
• SKaiNET Graph DSL support. ([GitHub][3])
• IREE StableHLO input format, compiler, runtime, and CPU deployment docs. ([IREE][4])

Acceptance criteria:

• A checked-in developer note defines the supported SKaiNET→StableHLO→IREE CPU contract, including entrypoint rules, tensor shape expectations, and supported ops for M1.
• At least one sequential model and one DAG/Graph DSL model export to StableHLO and compile with iree-compile for --iree-hal-local-target-device-backends=llvm-cpu.
• The resulting module runs with iree-run-module on a local CPU device.
• The exact tool versions or package versions used for the baseline are recorded.
• The issue documents the project license as MIT for SKaiNET