feat!: remove cloudzap

[fredrikaverpil]

Why?

• We want to default to slog and remove zap

What?

• Breaking changes as zap is removed!
  • cloudrunner.Logger is removed, use slog.InfoContext instead
  • No-op NewErrorLogger is removed
  • Signature changes:

    - func WithLoggerFields(ctx context.Context, fields ...zap.Field) context.Context {
    + func WithLoggerFields(ctx context.Context, args ...any) context.Context {
    
    - func ErrorDetails(err error) zap.Field
    + func ErrorDetails(err error) slog.Attr

Notes

• Closes fix(cloudzap): user service field (not name field) #812
• Logger middleware removed: The cloudzap.Middleware is no longer needed in HTTP/gRPC server chains because the cloudslog handler automatically extracts trace spans and custom attributes from context when you call slog.InfoContext(ctx, ...). We should NOT use slog.Info, we MUST use slog.InfoContext for this to work.