Add Gitea integration + ESLint setup

Phase 3: Gitea Integration
- Migration 012: app_settings table + gitea_commit_sha on endpoint_versions
- SettingsService: encrypted token storage (AES-256-GCM from JWT_SECRET)
- GiteaService: full REST API client — repo management, file CRUD,
  branches, commit history, diff/compare, pull requests, sync all
- giteaController + routes: 15 API endpoints for settings, branches,
  commits, PRs, endpoint info, sync
- VersionService hooks: auto-sync to Gitea on publish/draft (non-blocking)
- Frontend: Gitea tab in Settings (connection, sync status, branch mgmt),
  Gitea panel in EndpointEditor (file link, last commit SHA)
- docker-compose.gitea.yml: optional companion Gitea container
- Cache fix: index.html served with no-cache for instant deploys

ESLint Setup
- Backend: eslint 8 + @typescript-eslint configured
- Frontend: eslint 8 + @typescript-eslint + react-hooks + react-refresh
- Fixed 15 lint issues: unused imports, require statements, escapes,
  Function type, empty catch blocks
- Added npm run lint / lint:fix scripts

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docker-compose.gitea.yml

@@ -0,0 +1,44 @@
+# ============================================
+# KIS API Builder - Optional Gitea Integration
+# ============================================
+# Use alongside the main docker-compose:
+#   docker compose -f docker-compose.yml -f docker-compose.gitea.yml up -d
+#
+# For existing Gitea: skip this file, configure via Settings UI
+# ============================================
+
+services:
+  gitea:
+    image: gitea/gitea:1.22-rootless
+    container_name: kis-api-builder-gitea
+    restart: unless-stopped
+    environment:
+      - GITEA__database__DB_TYPE=sqlite3
+      - GITEA__server__ROOT_URL=${GITEA_URL:-http://localhost:${GITEA_PORT:-8010}}
+      - GITEA__server__HTTP_PORT=3000
+      - GITEA__security__INSTALL_LOCK=true
+      - GITEA__service__DISABLE_REGISTRATION=true
+    volumes:
+      - gitea_data:/var/lib/gitea
+      - gitea_config:/etc/gitea
+    ports:
+      - "${GITEA_PORT:-8010}:3000"
+    networks:
+      - kis-network
+    healthcheck:
+      test: ["CMD", "curl", "-f", "http://localhost:3000/api/v1/version"]
+      interval: 15s
+      timeout: 5s
+      retries: 5
+      start_period: 30s
+
+  app:
+    environment:
+      GITEA_URL: ${GITEA_URL:-http://gitea:3000}
+    depends_on:
+      gitea:
+        condition: service_healthy
+
+volumes:
+  gitea_data:
+  gitea_config: