Reorganize repository into professional structure with src/, include/, and user_apps/ directories

[Claude]

Restructured the repository into a more maintainable architecture with separate directories for kernel code, headers, and user applications. Added comprehensive System Architecture documentation explaining ioctl/read/write system call interactions with internal data structures.

Changes

Directory Structure

• Created src/ for kernel module source (message_slot.c)
• Created include/ for shared headers (message_slot.h)
• Created user_apps/ for user-space programs (message_sender.c, message_reader.c)
• Removed Linux_Kernel_Module/ directory
• Updated all include paths to reference ../include/message_slot.h

Build System

• New root Makefile builds both kernel module and user applications with single make command
• Supports individual targets: module, user_programs, clean, help
• Kernel module builds in src/ subdirectory, copies to root as message_slot.ko
• User applications build to user_apps/ directory with -Iinclude flag

Documentation

• Added "System Architecture" section (250+ lines) covering:
  • Component interaction diagram (user-space → system calls → kernel)
  • Deep dive into IOCTL commands (MSG_SLOT_CHANNEL, MSG_SLOT_SET_CEN)
  • Step-by-step WRITE and READ system call flows
  • Data structure hierarchies and lookup process
  • Memory lifecycle from module load through unload
  • Concurrency and safety considerations
• Updated "Project Structure" section to reflect new organization
• Updated build instructions and test examples to use new paths

Example Build Usage

# Build everything
make

# Build individual components
make module        # Kernel module only
make user_programs # User applications only
make clean         # Remove artifacts

Example Test Usage

./user_apps/message_sender /dev/slot0 1 0 "Hello, Kernel!"
./user_apps/message_reader /dev/slot0 1