refactor: Flatten directory structure

Move project files from uzdb/ subdirectory to root directory for cleaner project structure.

Changes:
- Move frontend/ to root
- Move internal/ to root
- Move build/ to root
- Move all config files (go.mod, wails.json, etc.) to root
- Remove redundant uzdb/ subdirectory nesting

Project structure is now:
├── frontend/        # React application
├── internal/        # Go backend
├── build/           # Wails build assets
├── doc/             # Design documentation
├── main.go          # Entry point
└── ...

🤖 Generated with Qoder

go.mod

@@ -0,0 +1,82 @@
+module uzdb
+
+go 1.25.0
+
+require (
+	github.com/gin-gonic/gin v1.12.0
+	github.com/go-sql-driver/mysql v1.9.3
+	github.com/lib/pq v1.12.0
+	github.com/wailsapp/wails/v2 v2.12.0
+	go.uber.org/zap v1.27.1
+	gorm.io/driver/sqlite v1.6.0
+	gorm.io/gorm v1.31.1
+	modernc.org/sqlite v1.48.0
+)
+
+require (
+	filippo.io/edwards25519 v1.1.0 // indirect
+	git.sr.ht/~jackmordaunt/go-toast/v2 v2.0.3 // indirect
+	github.com/bep/debounce v1.2.1 // indirect
+	github.com/bytedance/gopkg v0.1.3 // indirect
+	github.com/bytedance/sonic v1.15.0 // indirect
+	github.com/bytedance/sonic/loader v0.5.0 // indirect
+	github.com/cloudwego/base64x v0.1.6 // indirect
+	github.com/dustin/go-humanize v1.0.1 // indirect
+	github.com/gabriel-vasile/mimetype v1.4.12 // indirect
+	github.com/gin-contrib/sse v1.1.0 // indirect
+	github.com/go-ole/go-ole v1.3.0 // 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 v10.30.1 // indirect
+	github.com/goccy/go-json v0.10.5 // indirect
+	github.com/goccy/go-yaml v1.19.2 // indirect
+	github.com/godbus/dbus/v5 v5.1.0 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/gorilla/websocket v1.5.3 // indirect
+	github.com/jchv/go-winloader v0.0.0-20210711035445-715c2860da7e // indirect
+	github.com/jinzhu/inflection v1.0.0 // indirect
+	github.com/jinzhu/now v1.1.5 // indirect
+	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/klauspost/cpuid/v2 v2.3.0 // indirect
+	github.com/labstack/echo/v4 v4.13.3 // indirect
+	github.com/labstack/gommon v0.4.2 // indirect
+	github.com/leaanthony/go-ansi-parser v1.6.1 // indirect
+	github.com/leaanthony/gosod v1.0.4 // indirect
+	github.com/leaanthony/slicer v1.6.0 // indirect
+	github.com/leaanthony/u v1.1.1 // indirect
+	github.com/leodido/go-urn v1.4.0 // indirect
+	github.com/mattn/go-colorable v0.1.13 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/mattn/go-sqlite3 v1.14.22 // 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 v2.2.4 // indirect
+	github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/quic-go/qpack v0.6.0 // indirect
+	github.com/quic-go/quic-go v0.59.0 // indirect
+	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
+	github.com/rivo/uniseg v0.4.7 // indirect
+	github.com/samber/lo v1.49.1 // indirect
+	github.com/tkrajina/go-reflector v0.5.8 // indirect
+	github.com/twitchyliquid64/golang-asm v0.15.1 // indirect
+	github.com/ugorji/go/codec v1.3.1 // indirect
+	github.com/valyala/bytebufferpool v1.0.0 // indirect
+	github.com/valyala/fasttemplate v1.2.2 // indirect
+	github.com/wailsapp/go-webview2 v1.0.22 // indirect
+	github.com/wailsapp/mimetype v1.4.1 // indirect
+	go.mongodb.org/mongo-driver/v2 v2.5.0 // indirect
+	go.uber.org/multierr v1.10.0 // indirect
+	golang.org/x/arch v0.22.0 // indirect
+	golang.org/x/crypto v0.48.0 // indirect
+	golang.org/x/net v0.51.0 // indirect
+	golang.org/x/sys v0.42.0 // indirect
+	golang.org/x/text v0.34.0 // indirect
+	google.golang.org/protobuf v1.36.10 // indirect
+	modernc.org/libc v1.70.0 // indirect
+	modernc.org/mathutil v1.7.1 // indirect
+	modernc.org/memory v1.11.0 // indirect
+)
+
+// replace github.com/wailsapp/wails/v2 v2.12.0 => /root/go/pkg/mod