feat(backend,docker,docs): implement Go/Gin/SQLite REST API server, Docker containerization, and architecture specifications

- Implement standalone Go backend API server using Gin and pure-Go SQLite (modernc.org/sqlite)
- Add 11-table schema DDL migrations (000001_init.up.sql) based on DATA_TABLE.md
- Add seed data ingestion tool (cmd/seed) and static TypeScript content exporter (cmd/export-content)
- Add configuration loader (internal/config) supporting environment variables and .env files (HOST, PORT, DB_PATH, GIN_MODE, CORS_ALLOW_ORIGINS, AUTO_MIGRATE)
- Add lightweight multi-stage Dockerfile and docker-compose.yml with persistent SQLite volume
- Add comprehensive architecture specification (ARCHITECTURE.md) and REST API interface specification (API_INTERFACE.md)
- Harmonize frontend publications page to consume isHighlight flag from database-synced content

backend/go.mod

@@ -0,0 +1,49 @@
+module git.godopu.com/lab/landing_page/backend
+
+go 1.26.3
+
+require (
+	github.com/gin-gonic/gin v1.12.0
+	github.com/stretchr/testify v1.12.1
+	modernc.org/sqlite v1.57.0
+)
+
+require (
+	github.com/bytedance/gopkg v0.1.4 // indirect
+	github.com/bytedance/sonic v1.15.2 // indirect
+	github.com/bytedance/sonic/loader v0.5.2 // indirect
+	github.com/cloudwego/base64x v0.1.7 // indirect
+	github.com/dustin/go-humanize v1.0.1 // indirect
+	github.com/gabriel-vasile/mimetype v1.4.15 // indirect
+	github.com/gin-contrib/sse v1.1.1 // indirect
+	github.com/go-playground/locales v0.14.1 // indirect
+	github.com/go-playground/universal-translator v0.18.1 // indirect
+	github.com/go-playground/validator/v10 v10.30.3 // indirect
+	github.com/goccy/go-json v0.10.6 // indirect
+	github.com/goccy/go-yaml v1.19.2 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/klauspost/cpuid/v2 v2.4.0 // indirect
+	github.com/leodido/go-urn v1.5.0 // indirect
+	github.com/mattn/go-isatty v0.0.24 // indirect
+	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
+	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/ncruces/go-strftime v1.0.0 // indirect
+	github.com/pelletier/go-toml/v2 v2.4.3 // indirect
+	github.com/quic-go/qpack v0.6.0 // indirect
+	github.com/quic-go/quic-go v0.61.0 // indirect
+	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
+	github.com/twitchyliquid64/golang-asm v0.15.1 // indirect
+	github.com/ugorji/go/codec v1.3.2 // indirect
+	go.mongodb.org/mongo-driver/v2 v2.8.0 // indirect
+	go.yaml.in/yaml/v3 v3.0.5 // indirect
+	golang.org/x/arch v0.30.0 // indirect
+	golang.org/x/crypto v0.55.0 // indirect
+	golang.org/x/net v0.58.0 // indirect
+	golang.org/x/sys v0.47.0 // indirect
+	golang.org/x/text v0.41.0 // indirect
+	google.golang.org/protobuf v1.36.12 // indirect
+	modernc.org/libc v1.75.4 // indirect
+	modernc.org/mathutil v1.7.1 // indirect
+	modernc.org/memory v1.12.1 // indirect
+)