[codex] refactor us-equity strategy metadata and platform registry support

[Pigbibi]

What changed

• add canonical strategy metadata, display names, aliases, and compatibility helpers in UsEquityStrategies
• add shared platform-registry helper functions for platform repos to reuse
• clarify in tests and docs that supported_platforms is now a compatibility mirror, not the platform enablement source

Why

The repo was mixing strategy definition with platform enablement state. This refactor keeps strategy semantics in UsEquityStrategies and lets each runtime own its enabled/default/rollback profiles.

Impact

• no strategy logic or parameters changed
• canonical profile keys stay the same
• downstream runtimes can resolve aliases and build profile matrices from a shared helper instead of duplicating glue code

Validation

• pytest tests/test_catalog.py tests/test_platform_registry_support.py