Add comprehensive dependency checking at startup

New Function: check_dependencies()
- Verifies all 4 critical binaries exist before proceeding
- Binaries checked: mysqld, mysql, mysqldump, mysqladmin
- Clear error messages with installation instructions per OS
- Called early in main() before any interactive prompts

Impact:
- Prevents silent failures deep in the workflow
- Saves user time by failing fast with clear error messages
- Provides helpful package installation instructions
- Supports CentOS/RHEL, Debian/Ubuntu, AlmaLinux
- Runs once at startup (not repeatedly)

Before: User could go through all 5 steps only to fail when
        mysqldump or mysqladmin was actually needed

After: Dependencies validated immediately, clear error if missing

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

modules/backup/mysql-restore-to-sql.sh

@@ -79,6 +79,57 @@ cleanup_on_exit() {
 # Set trap for signals
 trap cleanup_on_exit EXIT INT TERM
 
+################################################################################
+# DEPENDENCY CHECKING
+################################################################################
+
+# Verify all required binaries exist before proceeding
+# Returns 1 if any critical dependency is missing
+check_dependencies() {
+    local missing_deps=0
+    local missing_list=""
+
+    # Critical binaries required for script operation
+    local required_binaries=(
+        "mysqld:MySQL server daemon (required to start second instance)"
+        "mysql:MySQL client (required for database queries)"
+        "mysqldump:MySQL backup tool (required to create SQL dump)"
+        "mysqladmin:MySQL admin tool (required for shutdown)"
+    )
+
+    print_info "Verifying required dependencies..."
+
+    for bin_info in "${required_binaries[@]}"; do
+        local bin="${bin_info%:*}"
+        local description="${bin_info#*:}"
+
+        # Try to find the binary
+        if ! command -v "$bin" &> /dev/null; then
+            print_error "  Missing: $bin - $description"
+            missing_deps=$((missing_deps + 1))
+            missing_list="$missing_list  - $bin\n"
+        else
+            print_success "  Found: $bin"
+        fi
+    done
+
+    if [ "$missing_deps" -gt 0 ]; then
+        echo ""
+        print_error "MISSING $missing_deps REQUIRED DEPENDENCY/IES"
+        echo ""
+        echo "Please install the following packages:"
+        echo -e "$missing_list"
+        echo ""
+        echo "On CentOS/RHEL: yum install mysql mysql-server"
+        echo "On Debian/Ubuntu: apt-get install mysql-client mysql-server"
+        echo "On AlmaLinux: dnf install mysql mysql-server"
+        return 1
+    fi
+
+    print_success "All required dependencies found"
+    return 0
+}
+
 ################################################################################
 # UTILITY FUNCTIONS
 ################################################################################
@@ -1839,6 +1890,13 @@ step5_create_dump() {
 # creates SQL dump, and provides usage instructions
 # Handles errors and signal interrupts with proper cleanup
 main() {
+    # CRITICAL: Check all required dependencies before proceeding
+    if ! check_dependencies; then
+        press_enter
+        exit 1
+    fi
+
+    echo ""
     show_intro
     echo -n "Continue? (y/n, or 0 to cancel): "
     read -r start