chore: fix W:useless-whatis-entry lintian warnings

By default, help2man generates "manual page for foobar" for
manual files.

It is useless because there is no addtional information which
explains what deskflow is.

With --name option, .SH NAME section will be set correctly.

Before:

  .\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.49.3.
  .TH DESKFLOW-CLIENT "1" "June 2025" "deskflow-client v1.22.0.109, protocol v1.8" "User Commands"
  .SH NAME
  deskflow-client \- manual page for deskflow-client v1.22.0.109, protocol v1.8
  .SH SYNOPSIS
  .B deskflow-client
  [\fI\,OPTIONS\/\fR]
  .SH DESCRIPTION

After:

  .\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.49.3.
  .TH DESKFLOW-CLIENT "1" "July 2025" "deskflow-client v1.22.0.109, protocol v1.8" "User Commands"
  .SH NAME
  deskflow-client \- Keyboard and mouse sharing utility (Client)
  .SH SYNOPSIS
  .B deskflow-client
  [\fI\,OPTIONS\/\fR]
  .SH DESCRIPTION

Signed-off-by: Kentaro Hayashi <kenhys@xdump.org>

src/apps/CMakeLists.txt

@@ -10,11 +10,12 @@ if(UNIX AND NOT APPLE)
   endif()
 endif()
 
-function(generate_app_man TARGET)
+function(generate_app_man TARGET NAME)
   if(HELP2MAN)
     add_custom_command(
       TARGET ${target} POST_BUILD
         COMMAND QT_QPA_PLATFORM=minimal PATH=$<TARGET_FILE_DIR:${target}>:${PATH} ${HELP2MAN}
+          --name ${NAME}
           --include ${CMAKE_SOURCE_DIR}/src/apps/res/manpage.txt
           --no-info
           ${target}

src/apps/deskflow-client/CMakeLists.txt

@@ -45,7 +45,7 @@ if(APPLE)
   )
 elseif(UNIX)
   install(TARGETS ${target} DESTINATION bin)
-  generate_app_man(${target})
+  generate_app_man(${target} "${CMAKE_PROJECT_DESCRIPTION} \\(Client\\)")
 elseif(WIN32)
   install(
     TARGETS ${target}

src/apps/deskflow-core/CMakeLists.txt

@@ -40,7 +40,7 @@ if(APPLE)
   )
 elseif(UNIX)
   install(TARGETS ${target} DESTINATION bin)
-  generate_app_man(${target})
+  generate_app_man(${target} "${CMAKE_PROJECT_DESCRIPTION}")
 elseif(WIN32)
   install(
     TARGETS ${target}

src/apps/deskflow-gui/CMakeLists.txt

@@ -84,5 +84,5 @@ elseif(APPLE)
   install(TARGETS ${target} BUNDLE DESTINATION .)
 else()
   install(TARGETS ${target} DESTINATION bin)
-  generate_app_man(${target})
+  generate_app_man(${target} "${CMAKE_PROJECT_DESCRIPTION} \\(GUI\\)")
 endif()

src/apps/deskflow-server/CMakeLists.txt

@@ -45,7 +45,7 @@ if(APPLE)
   )
 elseif(UNIX)
   install(TARGETS ${target} DESTINATION bin)
-  generate_app_man(${target})
+  generate_app_man(${target} "${CMAKE_PROJECT_DESCRIPTION} \\(Server\\)")
 elseif(WIN32)
   install(
     TARGETS ${target}