feat(web): densify all-books and series grids

Book cards on the library (all-books) page were oversized at full
window width, and both the all-books and series grids showed only
2 columns on phones, making covers unnecessarily large on mobile.

Shift the all-books column ladder up one at every breakpoint
(2/4/5/6 -> 3/5/6/7) so the responsive reflow the grid is liked for
is preserved while every window size gets smaller cards; the series
grid gains a column at mobile only (2 -> 3), leaving md/lg untouched
per request. Dashboard carousel sizing (w-36/w-40) and the series
stacked-covers component are deliberately unchanged.

templ codegen and the tailwind build output commit with the source
change that produced them (repo convention).

templates/bookshelf.templ

@@ -303,7 +303,7 @@ templ BookShelf(
 						</button>
 					</template>
 				</div>
-				<div id="books-grid" class="grid grid-cols-2 md:grid-cols-4 lg:grid-cols-5 xl:grid-cols-6 gap-4">
+				<div id="books-grid" class="grid grid-cols-3 md:grid-cols-5 lg:grid-cols-6 xl:grid-cols-7 gap-4">
 					@BooksGrid(books, limit, offset, count, currentLibraryID)
 					if errorMessage != "" {
 						<div class="col-span-full mt-2 p-4 rounded-xl border" style="background-color: color-mix(in srgb, var(--status-danger) 10%, transparent); border-color: var(--status-danger);">