feat: add complete rtop system monitoring tool with cpu, memory, process, network, disk, and filesystem modules

Implement the initial project structure for rtop, a terminal-based system monitor written in C, including header files for all monitoring subsystems (cpu.h, memory.h, process.h, network.h, disk.h, filesystem.h, system.h, terminal.h, display.h), a Makefile with static linking and debug build support, a .gitignore for object files, a CHANGELOG documenting version 0.1.0, and a comprehensive README with build instructions, usage examples, and feature descriptions covering per-core CPU utilization, memory/swap stats, process listing with sort options, network interface rates, disk I/O, and filesystem usage with color-coded output and terminal resize handling.

Makefile

@@ -0,0 +1,34 @@
+# retoor <retoor@molodetz.nl>
+
+CC = gcc
+CFLAGS = -Wall -Wextra -Werror -pedantic -std=c99 -O3 -march=native -D_POSIX_C_SOURCE=200809L -D_GNU_SOURCE
+LDFLAGS = -static
+SRCDIR = src
+INCDIR = include
+OBJDIR = obj
+
+SOURCES = $(wildcard $(SRCDIR)/*.c)
+OBJECTS = $(SOURCES:$(SRCDIR)/%.c=$(OBJDIR)/%.o)
+TARGET = rtop
+
+.PHONY: all clean debug
+
+all: $(TARGET)
+
+debug: CFLAGS += -g -DDEBUG
+debug: $(TARGET)
+
+$(TARGET): $(OBJECTS)
+	$(CC) $(OBJECTS) -o $@ $(LDFLAGS) 2>/dev/null || $(CC) $(OBJECTS) -o $@
+
+$(OBJDIR)/%.o: $(SRCDIR)/%.c | $(OBJDIR)
+	$(CC) $(CFLAGS) -I$(INCDIR) -c $< -o $@
+
+$(OBJDIR):
+	mkdir -p $(OBJDIR)
+
+clean:
+	rm -rf $(OBJDIR) $(TARGET)
+
+install: $(TARGET)
+	install -m 755 $(TARGET) /usr/local/bin/