Updated the document signing system to use a unified Blazor Auto (Server+WASM hybrid) frontend. Replaced client-side API calls with server-side authentication and data loading via `EnvelopeReceiverAuthorizationService` and `EnvelopeReceiverPageDataService`.
- Updated `/envelope/{key}` route to use MediatR for data loading.
- Integrated PDF.js 3.11.174 for rendering with configurable quality.
- Removed iText7 dependency due to GPL license issues.
- Introduced per-envelope cookies for receiver authentication.
- Cached signatures now loaded from distributed cache.
- Replaced redundant client-side API calls with server-side logic.
- Improved security and performance with server-side authorization.
These changes streamline the workflow, enhance security, and align the system with modern Blazor Server practices.
Prepare for Blazor Server/Auto migration by documenting current
WASM-specific culture initialization approach and providing
detailed migration checklist in COPILOT_CONTEXT.md.
Removed a redundant entry for the root route (`/`) in the
`ReceiverUI Route Structure` section of the documentation.
Both entries referenced the same file (`Index.razor`) and
served the same purpose, making the duplication unnecessary.
Replaced `COPILOT_CONTEXT_EN.md` with `COPILOT_CONTEXT.md`
in the `ProjectSection(SolutionItems)` of the solution file
`EnvelopeGenerator.sln` to reflect updated documentation.
