refactor(handlers): consume port interfaces, wire media+upload assembly (Task 25+26)

- H now holds only small port interfaces (UserStore/LibraryStore/BookStore/
  ProgressStore/BookmarkStore/RateLimiter/Scanner/Media/UploadSessions);
  NewRouter is the composition root distributing *store.Store and *redispkg.R
- ports.Media gains EnsurePage; ChaptersOf returns ports.Chapter (media's
  local duplicate dropped); *media.M now provably satisfies ports.Media;
  ports.UploadSessions gains LibraryID for root validation before Complete
- content.go: duplicated page-index cache + cover self-heal + page extract
  logic removed in favor of media service — same redis keys, same contract;
  path traversal check stays in handler (403 semantics preserved)
- getLibrary/getLibRow merged into getLib(c, id); idParam helper dedupes
  :id parsing; isUnique replaced by ports.IsUniqueViolation (Task 28 partial)
- main.go assembles media + upload and passes upload.U as scanner Sweeper

Full gate green: gofmt, vet, go test -p 1 (real PG+Redis, 0 skip)

backend/cmd/webui/handlers/libraries.go

@@ -16,6 +16,7 @@ import (
 
 	"booklib/internal/bookfile"
 	"booklib/internal/media"
+	"booklib/internal/ports"
 	"booklib/internal/store"
 )
 
@@ -23,7 +24,7 @@ import (
 func (h *H) libRoot(c *gin.Context, lib store.Library) (string, bool) {
 	root := filepath.Clean(lib.RootPath)
 	books := filepath.Clean(h.cfg.BooksDir)
-	if !filepath.IsAbs(root) || (root != books && !strings.HasPrefix(root, books+string(os.PathSeparator))) {
+	if !filepath.IsAbs(root) || !bookfile.Contains(books, root) {
 		err(c, http.StatusForbidden, "forbidden", "library root outside books dir")
 		return "", false
 	}
@@ -34,8 +35,22 @@ func (h *H) libRoot(c *gin.Context, lib store.Library) (string, bool) {
 	return root, true
 }
 
+// getLib 查库行,404/503/500 已回复(原 getLibrary/getLibRow 合一,Task 25)
+func (h *H) getLib(c *gin.Context, id int64) (store.Library, bool) {
+	l, e := h.libs.GetLibrary(c, id)
+	if e != nil {
+		if errors.Is(e, pgx.ErrNoRows) {
+			err(c, http.StatusNotFound, "not_found", "no such library")
+			return store.Library{}, false
+		}
+		dbErr(c, e)
+		return store.Library{}, false
+	}
+	return l, true
+}
+
 func (h *H) ListLibraries(c *gin.Context) {
-	libs, e := h.st.ListLibraries(c)
+	libs, e := h.libs.ListLibraries(c)
 	if e != nil {
 		dbErr(c, e)
 		return
@@ -68,9 +83,9 @@ func (h *H) CreateLibrary(c *gin.Context) {
 		return
 	}
 	root := filepath.Join(filepath.Clean(h.cfg.BooksDir), safe)
-	id, e := h.st.CreateLibrary(c, req.Name, root)
+	id, e := h.libs.CreateLibrary(c, req.Name, root)
 	if e != nil {
-		if isUnique(e) {
+		if ports.IsUniqueViolation(e) {
 			err(c, http.StatusConflict, "exists", "name taken")
 			return
 		}
@@ -80,26 +95,12 @@ func (h *H) CreateLibrary(c *gin.Context) {
 	c.JSON(http.StatusCreated, gin.H{"id": id, "name": req.Name, "root_path": root})
 }
 
-func (h *H) getLibrary(c *gin.Context) (store.Library, bool) {
-	id, e := strconv.ParseInt(c.Param("id"), 10, 64)
-	if e != nil {
-		err(c, http.StatusBadRequest, "bad_request", "bad id")
-		return store.Library{}, false
-	}
-	lib, e := h.st.GetLibrary(c, id)
-	if e != nil {
-		if errors.Is(e, pgx.ErrNoRows) {
-			err(c, http.StatusNotFound, "not_found", "no such library")
-			return store.Library{}, false
-		}
-		dbErr(c, e)
-		return store.Library{}, false
-	}
-	return lib, true
-}
-
 func (h *H) ScanLibrary(c *gin.Context) {
-	lib, ok := h.getLibrary(c)
+	id, ok := idParam(c)
+	if !ok {
+		return
+	}
+	lib, ok := h.getLib(c, id)
 	if !ok {
 		return
 	}
@@ -111,7 +112,11 @@ func (h *H) ScanLibrary(c *gin.Context) {
 }
 
 func (h *H) Upload(c *gin.Context) {
-	lib, ok := h.getLibrary(c)
+	id, ok := idParam(c)
+	if !ok {
+		return
+	}
+	lib, ok := h.getLib(c, id)
 	if !ok {
 		return
 	}
@@ -155,7 +160,7 @@ func (h *H) Upload(c *gin.Context) {
 			err(c, http.StatusInternalServerError, "internal", "create tmp")
 			return
 		}
-		// O_EXCL collision — retry with fresh uniquePath.
+		// O_EXCL collision — retry with fresh UniquePath.
 	}
 	if out == nil {
 		err(c, http.StatusConflict, "conflict", "too many concurrent uploads with same name")