feat: run.sh restart/stop/status + real DB connector + GitLab CI

1. run.sh: start/stop/restart/status/logs/build/test
   - PID file management in .pids/
   - Colored output, health check wait, log files
   - Auto alembic migrate on start

2. DB Connector (replaces mock aiomysql):
   - MySQL: aiomysql (connect/query/dml/test)
   - PostgreSQL: asyncpg (connect/query/dml/test)
   - SQLite: sqlite3 via executor (connect/query/dml/test)
   - Unified interface: DBConnector.test_connection/execute_query/execute_dml
   - Connection test returns version + latency

3. GitLab CI/CD pipeline:
   - test: backend pytest + frontend build
   - build: Docker images (manual trigger)
   - deploy: SSH deploy (manual trigger)
   - Cache: pip + node_modules

Tests: 128 passing, frontend build: OK

.gitlab-ci.yml

@@ -0,0 +1,97 @@
+stages:
+  - test
+  - build
+  - deploy
+
+variables:
+  PIP_CACHE_DIR: "$CI_PROJECT_DIR/.cache/pip"
+
+# Cache
+cache:
+  key: "${CI_COMMIT_REF_SLUG}"
+  paths:
+    - backend/venv/
+    - frontend/node_modules/
+    - .cache/pip/
+
+# ===== Test Stage =====
+
+backend-test:
+  stage: test
+  image: python:3.11-slim
+  before_script:
+    - cd backend
+    - python -m venv venv
+    - source venv/bin/activate
+    - pip install -r requirements.txt -q
+  script:
+    - source venv/bin/activate
+    - python -m pytest tests/ -v --tb=short --junitxml=report.xml
+  artifacts:
+    reports:
+      junit: backend/report.xml
+    when: always
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
+    - if: '$CI_COMMIT_BRANCH == "master"'
+
+frontend-build:
+  stage: test
+  image: node:20-alpine
+  before_script:
+    - cd frontend
+    - npm ci
+  script:
+    - npm run build
+  artifacts:
+    paths:
+      - frontend/dist/
+    expire_in: 1 day
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
+    - if: '$CI_COMMIT_BRANCH == "master"'
+
+# ===== Build Stage =====
+
+docker-build:
+  stage: build
+  image: docker:24
+  services:
+    - docker:24-dind
+  variables:
+    DOCKER_TLS_CERTDIR: "/certs"
+  before_script:
+    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" "$CI_REGISTRY" 2>/dev/null || true
+  script:
+    - docker build -t $CI_REGISTRY_IMAGE/backend:$CI_COMMIT_SHORT_SHA ./backend
+    - docker build -t $CI_REGISTRY_IMAGE/frontend:$CI_COMMIT_SHORT_SHA ./frontend
+    - docker push $CI_REGISTRY_IMAGE/backend:$CI_COMMIT_SHORT_SHA 2>/dev/null || true
+    - docker push $CI_REGISTRY_IMAGE/frontend:$CI_COMMIT_SHORT_SHA 2>/dev/null || true
+    - echo "Build complete: $CI_COMMIT_SHORT_SHA"
+  rules:
+    - if: '$CI_COMMIT_BRANCH == "master"'
+      when: manual
+  tags:
+    - docker
+
+# ===== Deploy Stage =====
+
+deploy:
+  stage: deploy
+  image: alpine:3.19
+  before_script:
+    - apk add --no-cache openssh-client
+    - eval $(ssh-agent -s)
+    - echo "$DEPLOY_SSH_KEY" | tr -d '\r' | ssh-add -
+    - mkdir -p ~/.ssh && chmod 700 ~/.ssh
+    - echo "$DEPLOY_SSH_HOST_KEY" > ~/.ssh/known_hosts 2>/dev/null || true
+  script:
+    - ssh $DEPLOY_USER@$DEPLOY_HOST "cd $DEPLOY_PATH && docker compose pull && docker compose up -d && echo 'Deploy done'"
+  environment:
+    name: production
+    url: http://$DEPLOY_HOST
+  rules:
+    - if: '$CI_COMMIT_BRANCH == "master"'
+      when: manual
+  tags:
+    - deploy