fix(core): share native model defaults with v1 config migration - #45760

Summary

V1 model configuration with only modalities.input, modalities.output, or tool_call populated the other capabilities with false and empty arrays. This could disable tools or remove supported outputs despite those fields being omitted.

• Share one capability-default factory between native model creation and V1 config migration.
• Use native defaults for omitted capability fields: tools enabled, text/image input, and text output.
• Preserve explicit values, including tool_call: false and empty modality arrays. Leave wholly omitted capabilities unset so existing catalog inheritance is unchanged.

Regression coverage

Compare complete catalog models through normalization and the real config-provider path, not only schema validity:

• Seven capability-default and explicit-override cases.
• Inherited provider SDK, endpoint, headers, and body without repeating them per model.
• Model-specific SDK/endpoint, ID, name, limits, costs, and ordinary variant overrides, including applying the selected variant.
• Explicit zero pricing and defaulted cache costs.
• Preservation of existing catalog metadata when V1 fields are omitted.

This fixes capability defaults; it does not change disabled-variant handling or claim request-level provider compatibility is fully audited.

Validation

• Before the fix: five of seven capability parity cases failed.
• After the fix: 81 scoped Core tests and four Schema config tests pass.
• Core typecheck passes with bun typecheck --singleThreaded (the parallel compiler hit the shared host thread limit).
• Schema typecheck, Prettier, and git diff --check pass.

Requested by: @rekram1-node (Aiden via Slack)