feat: Add detailed simulation to remaining simple organs

This commit applies a detailed physiological model to all remaining simple organ classes, bringing them to a level of complexity consistent with the Heart, Lungs, and Brain.

Updates include:
- Esophagus: Simulates peristalsis and bolus movement.
- Stomach: Implements a gastric state machine for digestion.
- Intestines: Adds segments (duodenum, jejunum, etc.) and simulates absorption.
- Pancreas: Differentiates endocrine and exocrine functions.
- Gallbladder: Simulates storing, concentrating, and releasing bile.
- Kidneys: Models nephrons, GFR, and electrolyte balance.
- Bladder: Implements a micturition cycle with pressure dynamics.
- Spleen: Models red and white pulp for blood filtering and immunity.

include/MedicalLib/Bladder.h

@@ -1,24 +1,67 @@
 #pragma once
 
 #include "Organ.h"
+#include <string>
 
 /**
- * @brief Represents the Bladder.
+ * @brief Represents the state of the bladder muscles and sphincters.
+ */
+enum class MicturitionState {
+    FILLING,
+    FULL,
+    VOIDING
+};
+
+/**
+ * @brief Represents the Bladder, which stores urine.
  */
 class MEDICAL_LIB_API Bladder : public Organ {
 public:
+    /**
+     * @brief Constructor for the Bladder class.
+     * @param id The ID of the organ.
+     */
     Bladder(int id);
+
+    /**
+     * @brief Updates the bladder's state over a time interval.
+     * @param deltaTime_s The time elapsed in seconds.
+     */
     void update(double deltaTime_s) override;
+
+    /**
+     * @brief Gets a string summary of the bladder's state.
+     * @return A string containing the bladder's state.
+     */
     std::string getSummary() const override;
 
-    // Note: A real model would get urine input from kidneys.
-    // For now, it will just fill at a constant rate.
+    /**
+     * @brief Adds urine from the kidneys.
+     * @param amount_ml The volume of urine to add.
+     */
     void addUrine(double amount_ml);
 
-    double getCurrentVolume() const;
-    double getCapacity() const;
+    // --- Getters for Bladder State ---
+
+    /** @brief Gets the current volume of urine in the bladder in mL. */
+    double getVolume() const;
+
+    /** @brief Gets the current pressure inside the bladder in cmH2O. */
+    double getPressure() const;
+
+    /** @brief Gets the current state of the micturition cycle. */
+    MicturitionState getCurrentState() const;
 
 private:
-    double currentVolume; // in ml
-    double capacity; // in ml
+    // --- Helper to convert enum to string ---
+    std::string stateToString(MicturitionState state) const;
+
+    // --- Physiological Parameters ---
+    MicturitionState currentState;
+    double currentVolume_mL;
+    double pressure_cmH2O;
+    bool internalSphincterClosed;
+
+    const double capacity_mL = 500.0;
+    const double pressureThreshold_cmH2O = 40.0; // Pressure at which voiding reflex is strong
 };