feat: bootstrap MediaStationGo (Go + React rewrite of MediaStation)

Adopt the cropflre/nowen-video tech stack and rebuild the project from
scratch:

  - Backend: Go 1.25 + Gin + GORM + SQLite (WAL) + JWT + WebSocket hub.
    Layered packages config / database / model / repository / service /
    middleware / handler. Default admin (admin/admin123) seeded on first
    run; /api routes for auth, libraries, media, stream and admin
    panels. WebSocket scan-progress events at /api/ws.
  - Frontend: React 18 + Vite 5 + Tailwind 3.4 + Zustand + axios +
    react-router 6 + lucide-react + framer-motion + hls.js. Pages for
    Login / Home / Library / Search / MediaDetail / Player / Admin
    (Library, Users, Settings tabs).
  - Distribution: multi-arch Dockerfile (frontend -> backend -> Alpine
    runtime), docker-compose.yml, GitHub Actions for CI and GHCR
    publish, Makefile, env-prefixed config (MEDIASTATION_*).
  - Docs: README, CONTRIBUTING, .env.example, config.example.yaml.

Backend builds, vets and tests pass. Frontend builds via tsc -b && vite
build (250 kB JS / 16 kB CSS, gzipped 84 / 4 kB).

internal/handler/media.go

@@ -0,0 +1,132 @@
+// Package handler — library / media HTTP endpoints.
+package handler
+
+import (
+	"errors"
+	"net/http"
+	"strconv"
+
+	"github.com/gin-gonic/gin"
+
+	"github.com/ShukeBta/MediaStationGo/internal/service"
+)
+
+type createLibraryReq struct {
+	Name string `json:"name" binding:"required"`
+	Path string `json:"path" binding:"required"`
+	Type string `json:"type"`
+}
+
+func listLibrariesHandler(svc *service.Container) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		libs, err := svc.Media.ListLibraries(c.Request.Context())
+		if err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+			return
+		}
+		c.JSON(http.StatusOK, libs)
+	}
+}
+
+func createLibraryHandler(svc *service.Container) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		var req createLibraryReq
+		if err := c.ShouldBindJSON(&req); err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+			return
+		}
+		l, err := svc.Media.CreateLibrary(c.Request.Context(), req.Name, req.Path, req.Type)
+		if err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+			return
+		}
+		c.JSON(http.StatusOK, l)
+	}
+}
+
+func deleteLibraryHandler(svc *service.Container) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		id := c.Param("id")
+		if err := svc.Media.DeleteLibrary(c.Request.Context(), id); err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+			return
+		}
+		c.Status(http.StatusNoContent)
+	}
+}
+
+func scanLibraryHandler(svc *service.Container) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		id := c.Param("id")
+		// Run synchronously: small libraries return immediately, big ones can
+		// hit the (configurable) HTTP timeout. A future task queue can move
+		// this to a background worker.
+		res, err := svc.Scan.ScanLibrary(c.Request.Context(), id)
+		if err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+			return
+		}
+		c.JSON(http.StatusOK, res)
+	}
+}
+
+func listMediaHandler(svc *service.Container) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		id := c.Param("id")
+		page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
+		size, _ := strconv.Atoi(c.DefaultQuery("page_size", "50"))
+		items, total, err := svc.Media.ListMedia(c.Request.Context(), id, page, size)
+		if err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+			return
+		}
+		c.JSON(http.StatusOK, gin.H{
+			"items":     items,
+			"total":     total,
+			"page":      page,
+			"page_size": size,
+		})
+	}
+}
+
+func getMediaHandler(svc *service.Container) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		m, err := svc.Media.GetMedia(c.Request.Context(), c.Param("id"))
+		if err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+			return
+		}
+		if m == nil {
+			c.JSON(http.StatusNotFound, gin.H{"error": "not found"})
+			return
+		}
+		c.JSON(http.StatusOK, m)
+	}
+}
+
+func searchMediaHandler(svc *service.Container) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		q := c.Query("q")
+		limit, _ := strconv.Atoi(c.DefaultQuery("limit", "50"))
+		items, err := svc.Media.SearchMedia(c.Request.Context(), q, limit)
+		if err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+			return
+		}
+		c.JSON(http.StatusOK, gin.H{"items": items})
+	}
+}
+
+func streamHandler(svc *service.Container) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		err := svc.Stream.ServeFile(c.Writer, c.Request, c.Param("id"))
+		if errors.Is(err, service.ErrMediaNotFound) {
+			c.JSON(http.StatusNotFound, gin.H{"error": "not found"})
+			return
+		}
+		if err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+			return
+		}
+	}
+}