fix: generate capability role schemas from dotted defs

[FanouZeng-TT]

Summary

• split dotted capability role containers during schema preprocessing instead of generating Any aliases for the container itself
• regenerate the affected 2026-08-25 models so identity linking and fulfillment expose platform/business role models
• add regression coverage for the preprocessing rule and identity-linking business config validation

Why

common/identity_linking.json defines dev.ucp.common.identity_linking as a container with platform_schema and business_schema. The old flattening path renamed the container as a single $defs entry, which generated IdentityLinking1 = Any and dropped the business-role config.scopes constraints from the SDK surface.

The same container shape exists in shopping/fulfillment.json, so regenerating the pinned 2026-08-25 models also restores those role models.

Verification

• ./generate_models.sh 2026-08-25
• uv run python -m unittest tests.test_codegen_pipeline.SchemaNormalizationTest tests.test_codegen_pipeline.IdentityLinkingRoleSchemaTest
• uv run python -m unittest discover -s tests -p 'test_*.py'
• uv run ruff format --check preprocess_schemas.py tests/test_codegen_pipeline.py
• uv run ruff check preprocess_schemas.py tests/test_codegen_pipeline.py
• git diff --check
• uvx pre-commit run hooks were run individually: trailing-whitespace, end-of-file-fixer, check-yaml, check-json, shebang hooks, ruff, ruff-format, prettier, shellcheck, and codespell passed. The local check-added-large-files hook hung in pre-commit; equivalent verification found no newly added file over 500KB.