feat(podcasts): Download All queues in the LISTENING order + add-modal order dropdown

Download All previously queued in feed-native order — 'getting the
last chapter first doesn't help me'. Now the queue follows the feed's
effective listening order (§0 item 5b): QueueFeedDownloadsAs reads the
CALLER's order override and runs episodes through services.OrderEpisodes
(same helper as the sequence/reader/page surfaces — the consolidation
from item 5a landed with the reverse-order commit). Queue tickets
(SEQUENCE-stamped, item 4) make that enqueue order the claim order, so
chapters land in the order you'll actually listen.

Add modal (§0 item 5c): with 'Download all episodes now' checked, a
'Download order' select appears (pure-CSS :checked sibling reveal — no
JS island, CSP-clean). Its choice is the feed's INITIAL order override
(reader_settings upsert; 'feed' = no row) AND the queue order for the
initial batch. Per-book by design: the override IS the download order.

Test TestPodcastAddModalDownloadOrder: add with download_all+reverse →
the override row exists AND persisted tickets run position 3→1. Tickets
are asserted (not live queued rows) because the shared dev server's
worker legitimately races this test's queue — tickets survive every
state flip.

web/static/input.css

@@ -2141,3 +2141,9 @@
   animation: podcast-indeterminate 1.3s ease-in-out infinite;
 }
 
+/* ---------- Add-feed modal: order dropdown reveals with the
+   "Download all" checkbox (§0 item 5c) — pure CSS, no JS island. The
+   select is a sibling of the checkbox label's input. */
+.podcast-add-order { display: none; }
+#podcast-download-all:checked ~ .podcast-add-order { display: flex; }
+