[Server] Reorganize server handlers and transport structure for better organization

[CodeWithKyrian]

Reorganizes the internal server structure to improve code organization and maintainability.

Changes

Handler Reorganization

• Moved: JsonRpc/Handler → Server/Handler/JsonRpcHandler
• Reorganized: Server/RequestHandler/ → Server/Handler/Request/
• Reorganized: Server/NotificationHandler/ → Server/Handler/Notification/
• Moved: MethodHandlerInterface → Server/Handler/ namespace

Transport Structure

• Moved: TransportInterface → Server/Transport/ namespace
• Consolidated: All transport-related code in one location

Data Structure

• Moved: Page.php → Schema/ namespace
• Rationale: It's a data structure concern, not server logic

Why

Better Organization

• Logical grouping: Related code is now co-located
• Predictable structure: Easier to find and understand code
• Cleaner namespaces: More intuitive import statements

Separation of Concerns

• Server-specific: JsonRpcHandler is server implementation, not global protocol
• Protocol-agnostic: MessageFactory stays in JsonRpc/ for reusability
• Data vs Logic: Page is a data structure, not server logic

Breaking Changes

• Internal only: No public API changes
• Import updates: All internal references updated
• Namespace changes: Internal classes moved to new namespaces

[chr-hertel]

in general i'm fine with this change, couple of thoughts tho:

• the JsonRpcHandler is quite a central service - even if currently internal to the server i was expecting it to be useful with the client as well, but we can tackle that then anyways.
• moving the Page to the schema def makes sense - next step might be to have that PaginatedRequest base class :D
• the MessageFactory feels lonely, but maybe also something to revisit when working on the client.

[CodeWithKyrian]

• Yeah true, its internal to the server at the moment that's why I moved it. For the client, the handling process will be very much different I think, but as you said, we'll cross that bridge when we get there. .
• You read my mind!! +1 on that
• Sure!