fix: Normalize ASR MRoPE metadata for runtime

[suharvest]

What does this PR do?

Extends the existing runtime RoPE normalization to recognize checkpoint
metadata that combines rope_type: linear with mrope_section.

That combination describes an MRoPE layout used by Qwen3-ASR checkpoints, but
the runtime accepts the existing normalized default + mrope_section form.
Without this normalization, export preserves linear and the runtime does not
select its MRoPE path.

The input dictionary is copied rather than mutated. Ordinary linear RoPE
metadata without mrope_section remains unchanged.

Scope

• One production-line change in the existing normalization helper.
• Two focused regression tests.
• No model-name, local path, runtime, engine, or product-specific branches.

Validation

• Focused regression tests: 2 passed.
• Positive case verifies linear + mrope_section becomes
  default + mrope_section without mutating the source.
• Negative case verifies ordinary linear RoPE keeps linear semantics.
• Python syntax, focused formatting checks, git diff --check, and merge-tree
  validation pass.

This is a configuration-normalization regression test. A complete
export → build → inference validation requires the model and GPU environment
and is still requested from CI/device testing.

Closes #142.