feat: add health check endpoints for Bot and Web

- Web: add /health endpoint with PostgreSQL readiness check (returns 200+JSON or 503)
- Web: add /alive endpoint for liveness probe
- Bot: add BotHealthCheckHostedService serving /health on port 8081 via HttpListener
- Bot: expose port 8081 in Dockerfile and install wget for healthcheck
- compose.yaml: add healthcheck sections for bot and web services
- tests: add TDD tests for both health endpoints

Bump version -> 1.16.0

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

compose.yaml

@@ -49,7 +49,7 @@ services:
         crond -f
 
   bot:
-    image: git.codeanddice.ru/toutsu/gmrelay-bot:1.15.1
+    image: git.codeanddice.ru/toutsu/gmrelay-bot:1.16.0
     restart: always
     depends_on:
       db:
@@ -60,9 +60,14 @@ services:
       - "Telegram__MiniAppUrl=${TELEGRAM_MINI_APP_URL:-}"
     networks:
       - gmrelay
+    healthcheck:
+      test: ["CMD-SHELL", "wget -qO- http://localhost:8081/health || exit 1"]
+      interval: 10s
+      timeout: 5s
+      retries: 3
 
   web:
-    image: git.codeanddice.ru/toutsu/gmrelay-web:1.15.1
+    image: git.codeanddice.ru/toutsu/gmrelay-web:1.16.0
     restart: always
     depends_on:
       db:
@@ -78,6 +83,11 @@ services:
       - web_keys:/app/dataprotection-keys
     networks:
       - gmrelay
+    healthcheck:
+      test: ["CMD-SHELL", "wget -qO- http://localhost:8080/health || exit 1"]
+      interval: 10s
+      timeout: 5s
+      retries: 3
 
 volumes:
   pgdata: