feat: Add Doxygen documentation and Gitea workflow

This commit introduces Doxygen for documentation generation and a Gitea
workflow for continuous integration.

- Adds a `Doxyfile` to configure Doxygen to build a documentation
  website with diagrams.
- Updates `AGENTS.md` to require Doxygen-compatible comments for all
  code.
- Adds Doxygen comments to existing C++ source files to comply with
  the new standard.
- Creates a Gitea workflow (`.gitea/workflows/build.yml`) that:
  - Builds the project on every push.
  - Generates Doxygen documentation.
  - Uploads the compiled library and the documentation website as
    artifacts.

.gitea/workflows/build.yml

@@ -0,0 +1,33 @@
+name: Build and Test
+
+on: [push]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y g++ cmake doxygen graphviz
+
+      - name: Build
+        run: ./build.sh
+
+      - name: Generate Documentation
+        run: doxygen Doxyfile
+
+      - name: Upload Library Artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: medical-lib
+          path: build/lib
+
+      - name: Upload Documentation Artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: documentation
+          path: docs/html

AGENTS.md

@@ -31,6 +31,29 @@ To build the project, use the provided build scripts:
 
 The compiled library will be placed in `build/lib`, and the example executable will be in `build/examples/`.
 
+## Coding Standards
+
+### Doxygen Documentation
+
+All functions, classes, structs, enums, and public member variables must be documented using Doxygen-compatible comments. This ensures that the code is easy to understand and that high-quality documentation can be automatically generated.
+
+- Use `/** ... */` for multi-line comments.
+- Use `///` for single-line comments.
+- Use `@brief` to provide a short description.
+- Use `@param` to document function parameters.
+- Use `@return` to describe the return value.
+
+Example:
+```cpp
+/**
+ * @brief Calculates the Body Mass Index (BMI).
+ * @param weight_kg The weight in kilograms.
+ * @param height_m The height in meters.
+ * @return The calculated BMI.
+ */
+MEDICAL_LIB_API double calculateBMI(double weight_kg, double height_m);
+```
+
 ## Integration with Unreal Engine
 
 To use this library in an Unreal Engine plugin:

Doxyfile

@@ -0,0 +1,49 @@
+# Doxyfile 1.9.1
+
+# Project
+PROJECT_NAME           = "MedicalLib"
+PROJECT_NUMBER         = 1.0
+PROJECT_BRIEF          = "A C++ library for medical simulations"
+OUTPUT_DIRECTORY       = "docs"
+CREATE_SUBDIRS         = YES
+OUTPUT_LANGUAGE        = English
+BRIEF_MEMBER_DESC      = YES
+REPEAT_BRIEF           = YES
+
+# Sources
+INPUT                  = ./include ./src
+FILE_PATTERNS          = *.h *.cpp
+RECURSIVE              = YES
+EXCLUDE_PATTERNS       =
+EXCLUDE_SYMBOLS        =
+
+# HTML
+GENERATE_HTML          = YES
+HTML_OUTPUT            = html
+HTML_FILE_EXTENSION    = .html
+HTML_HEADER            =
+HTML_FOOTER            =
+HTML_STYLESHEET        =
+HTML_COLORSTYLE_HUE    = 220
+HTML_COLORSTYLE_SAT    = 100
+HTML_COLORSTYLE_GAMMA  = 80
+
+# Diagrams
+HAVE_DOT               = YES
+DOT_TOOL_PATH          =
+DOTFILE_DIRS           =
+UML_LOOK               = YES
+UML_LIMIT_NUM_FIELDS   = 10
+TEMPLATE_RELATIONS     = YES
+CALL_GRAPH             = YES
+CALLER_GRAPH           = YES
+GRAPHICAL_HIERARCHY    = YES
+DIRECTORY_GRAPH        = YES
+DOT_IMAGE_FORMAT       = png
+INTERACTIVE_SVG        = NO
+DOT_GRAPH_MAX_NODES    = 50
+MAX_DOT_GRAPH_DEPTH    = 0
+DOT_TRANSPARENT        = NO
+DOT_MULTI_TARGETS      = YES
+GENERATE_LEGEND        = YES
+DOT_CLEANUP            = YES

src/MedicalLib.cpp

@@ -1,6 +1,13 @@
 #include "MedicalLib/MedicalLib.h"
 #include <stdexcept>
 
+/**
+ * @brief Calculates the Body Mass Index (BMI).
+ * @param weight_kg The weight in kilograms.
+ * @param height_m The height in meters.
+ * @return The calculated BMI.
+ * @throws std::invalid_argument if height or weight are non-positive.
+ */
 double calculateBMI(double weight_kg, double height_m) {
     if (height_m <= 0) {
         throw std::invalid_argument("Height must be positive.");

src/Patient.cpp

@@ -2,7 +2,11 @@
 #include <random>
 #include <algorithm> // For std::clamp
 
-// Helper function to generate random fluctuations
+/**
+ * @brief Helper function to generate random fluctuations from a normal distribution.
+ * @param stddev The standard deviation of the distribution.
+ * @return A random value.
+ */
 double getFluctuation(double stddev) {
     static std::random_device rd;
     static std::mt19937 gen(rd());
@@ -10,6 +14,11 @@ double getFluctuation(double stddev) {
     return d(gen);
 }
 
+/**
+ * @brief Initializes a new patient with baseline vital signs.
+ * @param patientId The ID for the new patient.
+ * @return A Patient struct with default healthy values.
+ */
 Patient initializePatient(int patientId) {
     Patient patient;
     patient.patientId = patientId;
@@ -22,6 +31,12 @@ Patient initializePatient(int patientId) {
     return patient;
 }
 
+/**
+ * @brief Updates the patient's vital signs based on the time elapsed.
+ * This function simulates minor, random fluctuations around a healthy baseline.
+ * @param patient The patient to update.
+ * @param deltaTime_s The time elapsed in seconds.
+ */
 void updatePatient(Patient& patient, double deltaTime_s) {
     // Baseline healthy values
     const double baseline_hr = 75.0;