feat(templates): add BooksGrid component for reusable book grid rendering

Create new BooksGrid templ component that renders a grid of books with pagination. This component can be reused across multiple pages and returns HTML for HTMX updates.

- Add books_grid.templ with BooksGrid component
- Renders book cards using existing BookCard component
- Includes pagination controls with HTMX attributes
- Accepts books list, pagination params, and library ID
- Generated books_grid_templ.go from templ compiler

templates/books_grid.templ

@@ -0,0 +1,48 @@
+package templates
+
+import "bookhoard/internal/handlers"
+
+templ BooksGrid(books []handlers.BookInfo, limit int, offset int, count int, currentLibraryID string) {
+	<div id="books-grid" class="grid grid-cols-2 md:grid-cols-4 lg:grid-cols-6 xl:grid-cols-8 gap-4">
+		if len(books) > 0 {
+			for _, book := range books {
+				@BookCard(book)
+			}
+		} else {
+			<!-- Empty state -->
+			<div class="col-span-full text-center py-12" style="color: var(--text-secondary);">
+				<p class="text-lg mb-2">📚 No books found</p>
+				<p class="text-sm">Try adjusting your filters or add some books to your library.</p>
+			</div>
+		}
+	</div>
+	<!-- Pagination -->
+	<div id="pagination" class="mt-6 flex justify-center gap-2">
+		if count > 0 {
+			<button
+				type="button"
+				class="px-4 py-2 rounded-lg border disabled:opacity-50"
+				style="border-color: var(--border); color: var(--text-primary);"
+				hx-get="/api/media-items/search?library_id={ currentLibraryID }&limit={ limit }&offset={ offset - limit }"
+				hx-target="#books-grid"
+				hx-include="#filter-form"
+				disabled?={ offset <= 0 }
+			>
+				← Previous
+			</button>
+			<span class="px-4 py-2" style="color: var(--text-secondary);">
+				Page { offset / limit + 1 }
+			</span>
+			<button
+				class="px-4 py-2 rounded-lg border disabled:opacity-50"
+				style="border-color: var(--border); color: var(--text-primary);"
+				hx-get="/api/media-items/search?library_id={ currentLibraryID }&limit={ limit }&offset={ offset + limit }"
+				hx-target="#books-grid"
+				hx-include="#filter-form"
+				disabled?={ offset+limit >= count }
+			>
+				Next →
+			</button>
+		}
+	</div>
+}