fc-025 Product module integration

Pages

• Product module shape explains the Go package boundary for provider adapters, view models, framework pages, and event projection.
• Portal modules describes how product modules expose deterministic Go-first GX pages through the portal framework contract.
• Portal host contract records the host context, metadata, and routing responsibilities that product modules can rely on.
• Portal shell shows the shell component shape that modules compose from .gx, Go, and shared Bus UI primitives.