Add HS256 JWT authentication to both HTTP and gRPC servers using
Kratos jwt middleware with selector to skip auth for public share
endpoints (GetShareInfo, DownloadShare). Wire DI updated to inject
conf.Auth into server constructors.
Create internal/server package with HTTP and gRPC server constructors
using Kratos transport layer. Includes Wire provider set for DI,
recovery/tracing/logging middleware, and graceful nil-safe config handling.
Fix .gitignore 'server' pattern to only match root-level binary.