Add OpenAPI/Swagger documentation

- Add Swagger dependencies to go.mod
- Annotate all API endpoints with Swagger comments
- Add Swagger UI at /api/v1/docs endpoint
- Auto-generate Swagger docs in Dockerfile build
- Update README with API documentation link

go.mod

@@ -5,11 +5,13 @@ go 1.24.0
 toolchain go1.24.10
 
 require (
-	github.com/go-chi/chi/v5 v5.2.3 // indirect
-	github.com/go-chi/cors v1.2.2 // indirect
-	github.com/golang-jwt/jwt/v5 v5.3.0 // indirect
-	github.com/google/uuid v1.6.0 // indirect
-	github.com/joho/godotenv v1.5.1 // indirect
-	github.com/mattn/go-sqlite3 v1.14.32 // indirect
-	golang.org/x/crypto v0.45.0 // indirect
+	github.com/go-chi/chi/v5 v5.2.3
+	github.com/go-chi/cors v1.2.2
+	github.com/golang-jwt/jwt/v5 v5.3.0
+	github.com/google/uuid v1.6.0
+	github.com/joho/godotenv v1.5.1
+	github.com/mattn/go-sqlite3 v1.14.32
+	github.com/swaggo/http-swagger v1.3.4
+	github.com/swaggo/swag v1.16.4
+	golang.org/x/crypto v0.45.0
 )