Update portal architecture to support SSR and route-based rendering instead of CSR pages

[justin-phxm]

Refactor the portal architecture to support server-side rendering (SSR) and migrate away from client-side rendered (CSR) page patterns to route-based rendering.

Goals

• Introduce SSR support across portal entry points where appropriate.
• Replace CSR-only page architecture with route-driven rendering.
• Ensure route definitions and data loading patterns align with SSR lifecycle requirements.
• Preserve existing user-facing behavior and styling during migration.

Scope

• Audit current CSR page structure and identify migration path per page/section.
• Implement SSR-compatible route handlers and page composition.
• Move client-side data-fetching logic to server-capable patterns where needed.
• Update shared layout/navigation logic to work with SSR routes.
• Validate hydration behavior and prevent SSR/CSR mismatch issues.

Acceptance Criteria

• Portal pages are accessible via route-based architecture (not CSR page mounting).
• SSR renders key portal routes successfully in production mode.
• No critical regressions in navigation, auth-gated views, or page-level data loading.
• Build and deploy pipeline passes with SSR-enabled portal routes.
• Developer documentation is updated with new architecture and routing conventions.

Notes

• Prioritize incremental migration to reduce risk.
• Track known SSR-incompatible components and resolve or isolate them.