Feat: Implement interconnected organ simulation

This commit refactors the organ simulation to enable dynamic interactions between organs, replacing the previous "faked" or hardcoded connections.

Key changes include:
- Major Refactoring: Changed the `Organ::update` method signature to `update(Patient& patient, double deltaTime_s)`, allowing organs to access the shared patient state and other organs. This was propagated to all organ classes.
- Blood Chemistry Model: Introduced a central `Blood` struct in the `Patient` model to track shared resources like oxygen, CO2, glucose, and toxins.
- Organ System Interconnections:
    - Lungs & Brain: Lungs now perform gas exchange affecting the blood. The brain consumes O2, produces CO2, and its GCS is affected by hypoxia/hypercapnia.
    - Liver-Gallbladder: Gallbladder now receives bile directly from the liver's production rate.
    - Digestive System: Stomach passes chyme to the intestines, which absorb glucose into the blood. The pancreas responds to blood glucose changes.
    - Renal System: Kidneys' GFR is now influenced by the heart's aortic pressure, and they produce urine that fills the bladder directly.
    - Cardiovascular & Neurological: The heart rate responds to hypoxia, and the brain uses live aortic pressure from the heart.
- Comprehensive Test Scenario: Updated the main example to include a 60-second simulation with a meal and a lung injury event to verify the new interconnected system.

This creates a more realistic and scalable physiological simulation framework where organ behaviors are emergent from their interactions.

examples/main.cpp

@@ -8,31 +8,69 @@
 #include "MedicalLib/Patient.h"
 #include "MedicalLib/Organ.h"
 #include "MedicalLib/Heart.h"
+#include "MedicalLib/Stomach.h"
+#include "MedicalLib/Lungs.h"
 
 int main() {
     // Initialize a new patient with a 12-lead heart
     Patient patient = initializePatient(1, 12);
     std::cout << "Patient created with ID: " << patient.patientId << std::endl;
 
+    // Introduce a toxin load to the blood for the liver to clear
+    patient.blood.toxins_au = 100.0;
+    std::cout << "Initial toxin load of 100.0 a.u. introduced.\n" << std::endl;
+
     // Simulate time passing and print a live summary
-    const double simulationTime_s = 10.0;
-    const double deltaTime_s = 0.05; // 20 Hz update rate for display
+    const double simulationTime_s = 60.0; // Run for a longer time to see effects
+    const double deltaTime_s = 0.1;
     const int numSteps = static_cast<int>(simulationTime_s / deltaTime_s);
 
-    std::cout << "\n--- Simulating " << simulationTime_s << " seconds of heart activity... ---" << std::endl;
+    // Get pointers to organs we want to interact with
+    Stomach* stomach = getOrgan<Stomach>(patient);
+    if(stomach) {
+        stomach->addSubstance(300.0); // Simulate eating a meal
+        std::cout << "A 300mL meal has been consumed." << std::endl;
+    }
+    Lungs* lungs = getOrgan<Lungs>(patient);
+
+
+    std::cout << "\n--- Simulating " << simulationTime_s << " seconds... ---" << std::endl;
 
     for (int i = 0; i < numSteps; ++i) {
+        double currentTime = i * deltaTime_s;
         // Clear console on systems that support ANSI escape codes
         #if defined(__linux__) || defined(__APPLE__)
         std::cout << "\033[2J\033[1;1H";
         #endif
 
+        // --- Event scripting ---
+        if (std::abs(currentTime - 20.0) < deltaTime_s/2.0) {
+            if (lungs) {
+                std::cout << "\n*** LUNG INJURY EVENT ***\n" << std::endl;
+                lungs->inflictDamage(0.8); // 80% damage
+            }
+        }
+
         updatePatient(patient, deltaTime_s);
 
-        std::cout << "Time: " << i * deltaTime_s << "s / " << simulationTime_s << "s\n" << std::endl;
-        std::cout << getOrganSummary(patient, "Heart") << std::endl;
+        std::cout << "Time: " << currentTime << "s / " << simulationTime_s << "s\n" << std::endl;
+        std::cout << "--- Blood Chemistry ---\n"
+                  << "SpO2: " << patient.blood.oxygenSaturation << " %\n"
+                  << "PaCO2: " << patient.blood.co2PartialPressure_mmHg << " mmHg\n"
+                  << "Glucose: " << patient.blood.glucose_mg_per_dL << " mg/dL\n"
+                  << "Toxins: " << patient.blood.toxins_au << " a.u.\n\n";
 
-        std::this_thread::sleep_for(std::chrono::milliseconds(50));
+        std::cout << getOrganSummary(patient, "Heart") << std::endl;
+        std::cout << getOrganSummary(patient, "Lungs") << std::endl;
+        std::cout << getOrganSummary(patient, "Brain") << std::endl;
+        std::cout << getOrganSummary(patient, "Stomach") << std::endl;
+        std::cout << getOrganSummary(patient, "Intestines") << std::endl;
+        std::cout << getOrganSummary(patient, "Pancreas") << std::endl;
+        std::cout << getOrganSummary(patient, "Kidneys") << std::endl;
+        std::cout << getOrganSummary(patient, "Bladder") << std::endl;
+
+
+        std::this_thread::sleep_for(std::chrono::milliseconds(100));
     }
 
     std::cout << "\n--- Simulation Complete. Final State: ---\n" << std::endl;