feat(collections): Add library-aware filtering to collection detail pages

- Add library_id parameter to BuildSections and getViewAllURL functions
- Update dashboard handler to pass libraryID when building sections
- Add library_id query param support to collection detail page handler
- When library_id is provided, filter collection items by that library
- When no library_id, show all books (backward compatible)
- Reuses GetCollectionItemsForDashboard query for filtered results
- Preserves context when navigating from dashboard to collection detail

internal/handlers/dashboard.go

@@ -61,7 +61,7 @@ func (h *DashboardHandler) GetSections(c echo.Context) error {
 		return c.JSON(http.StatusInternalServerError, map[string]string{"error": "Failed to load dashboard sections"})
 	}
 
-	sectionData := BuildSections(sections)
+	sectionData := BuildSections(sections, libraryID)
 
 	return c.JSON(http.StatusOK, map[string]interface{}{"sections": sectionData})
 }
@@ -154,7 +154,7 @@ func (h *DashboardHandler) RestoreSystemCollection(c echo.Context) error {
 	return c.JSON(http.StatusOK, map[string]string{"message": "System collection restored to defaults"})
 }
 
-func BuildSections(sections []services.DashboardSection) []SectionData {
+func BuildSections(sections []services.DashboardSection, currentLibraryID string) []SectionData {
 	var result []SectionData
 
 	for _, ds := range sections {
@@ -177,7 +177,7 @@ func BuildSections(sections []services.DashboardSection) []SectionData {
 			Description:  ds.Description,
 			Icon:         ds.Icon,
 			Items:        bookCards,
-			ViewAllURL:   getViewAllURL(ds.CollectionID.String()),
+			ViewAllURL:   getViewAllURL(ds.CollectionID.String(), currentLibraryID),
 			Priority:     ds.Priority,
 		})
 	}
@@ -185,8 +185,11 @@ func BuildSections(sections []services.DashboardSection) []SectionData {
 	return result
 }
 
-func getViewAllURL(collectionID string) string {
+func getViewAllURL(collectionID string, libraryID string) string {
 	if collectionID != "" {
+		if libraryID != "" {
+			return "/collections/" + collectionID + "?library_id=" + libraryID
+		}
 		return "/collections/" + collectionID
 	}
 	return ""