refactor: consolidate strict provider/model reference parsing #99674

Summary

OpenClaw has repeated implementations of the same mechanical provider/model reference grammar across model catalog, config, Gateway startup, and plugin runtime paths. These copies trim and split on the first slash, normalize the provider id, preserve slash-containing model ids, and reject missing provider/model segments.

Exact Contract

• Input is a string provider/model reference.
• Trim surrounding whitespace and segment-edge whitespace.
• Split on the first / only.
• Require non-empty provider and model segments.
• Normalize the provider id through the model-catalog provider-id contract.
• Preserve model-id casing and any additional / characters.

Scope

• Add the mechanical parser to @openclaw/model-catalog-core.
• Migrate callers that already implement the exact normalized contract.
• Delete local copies and retain caller-specific return-shape adaptation only where necessary.
• Add focused canonical and migrated-caller tests.

Non-Goals

• Provider selection or fallback choice.
• Authentication, retryability, aliases, runtime routing, or provider-specific model-id normalization.
• Bare-model default-provider resolution.
• Compatibility or doctor migration behavior.
• A universal option-heavy parser.

Evidence / Completion

• Focused Vitest coverage for the canonical helper and migrated callers.
• Changed typecheck/lint/guard lanes and import-cycle proof.
• Package build proof because the model-catalog package surface changes.
• Production LOC reduction and search proof for removed duplicate implementations.