Initial commit: Complete Software Architecture course with 11 modules

- Added comprehensive course structure with 11 modules
- Included theoretical content, practical examples, and tasks
- Multi-language code examples (Java, Rust, Node.js, Python)
- Detailed analysis of architectural approaches and trade-offs
- Complete caching strategies documentation
- Architecture examples from real-world systems (Twitter, Netflix, Uber)
- Structured navigation and learning path
- Ready for educational use

modules/module5/sections/05-observability.md

@@ -0,0 +1,92 @@
+# Observability
+
+## Навигация
+- [🏠 Главная страница курса](../../../README.md)
+- [📚 Модуль 5](../README.md)
+
+---
+
+## Три столпа Observability
+
+### 1. Metrics (Метрики)
+- Количественные измерения
+- Агрегированные данные
+- Хорошо для мониторинга трендов
+
+### 2. Logs (Логи)
+- События с временными метками
+- Детальная информация
+- Хорошо для отладки
+
+### 3. Traces (Трассировки)
+- Путь запроса через систему
+- Временные зависимости
+- Хорошо для анализа производительности
+
+## Паттерны наблюдаемости
+
+### 1. Health Checks
+```java
+@Component
+public class HealthIndicator implements HealthIndicator {
+    @Override
+    public Health health() {
+        try {
+            // проверка зависимостей
+            boolean dbHealthy = checkDatabase();
+            boolean cacheHealthy = checkCache();
+            
+            if (dbHealthy && cacheHealthy) {
+                return Health.up()
+                    .withDetail("database", "UP")
+                    .withDetail("cache", "UP")
+                    .build();
+            } else {
+                return Health.down()
+                    .withDetail("database", dbHealthy ? "UP" : "DOWN")
+                    .withDetail("cache", cacheHealthy ? "UP" : "DOWN")
+                    .build();
+            }
+        } catch (Exception e) {
+            return Health.down(e).build();
+        }
+    }
+}
+```
+
+### 2. Custom Metrics
+```java
+@Component
+public class BusinessMetrics {
+    private final Counter ordersCreated;
+    private final Timer orderProcessingTime;
+    private final Gauge activeUsers;
+    
+    public BusinessMetrics(MeterRegistry meterRegistry) {
+        this.ordersCreated = Counter.builder("orders.created")
+            .description("Total orders created")
+            .register(meterRegistry);
+            
+        this.orderProcessingTime = Timer.builder("orders.processing.time")
+            .description("Order processing time")
+            .register(meterRegistry);
+            
+        this.activeUsers = Gauge.builder("users.active")
+            .description("Number of active users")
+            .register(meterRegistry, this, obj -> obj.getActiveUsersCount());
+    }
+    
+    public void recordOrderCreated() {
+        ordersCreated.increment();
+    }
+    
+    public void recordOrderProcessingTime(Duration duration) {
+        orderProcessingTime.record(duration);
+    }
+    
+    private int getActiveUsersCount() {
+        // логика подсчета активных пользователей
+        return 0;
+    }
+}
+```