feat(podcasts): unset listening order defaults to reversed (audiobook-first)

The per-feed listening order — the Order dropdown on the podcast page
and player — resolved its UNSET state to "native": feed document order,
which runs newest-first for classic RSS. This platform is audiobook-
first, so native started every book at its LAST chapter (verified on
live data: 7th Son position 1 = Bonus Episode #2, positions descending
through the chapters).

The unset fallback flips to "reverse" at every resolution site of that
ONE setting — the podcast page's list + dropdown (podcastOrderForFeed),
the player's feed chain (reader.go), and the download queue
(orderOverrideFor) — so the dropdown shows reversed selected, the page
renders in that order, and play/download follow. Stored overrides are
untouched (native stays a valid savable choice); no ordering semantics
changed; collections are untouched.

Pins: the flipped native expectation is changelogged in contract_pins;
new pins cover the sequence config carrying reverse, feed position 1
playing last, and the page dropdown rendering reverse selected for an
unset feed.

docs/contract_pins.md

@@ -649,3 +649,22 @@ episodes).
 - The quiet suggest fetch remains only as a fallback for trees the SSR
   never saw (client-side apply flows); embedded labels make it a no-op
   on refresh.
+
+## 2026-11-01 — unset podcast order defaults to reversed (audiobook-first)
+
+The per-feed listening order (the D5 `podcast_order:<feedID>` KV shown
+in the Order dropdown) resolved its UNSET state to "native" — feed
+document order, which runs newest-first for classic RSS, so an
+audiobook feed played its LAST chapter first. The unset default is now
+`reverse` at every resolution site of that one setting: the podcast
+page list + dropdown (`podcastOrderForFeed`), the player's feed chain
+(reader.go), and the download worker (`orderOverrideFor`).
+
+- Stored overrides are untouched: anyone who picked an order keeps it
+  (native remains a valid, savable choice).
+- No ordering semantics changed — `OrderEpisodes` and the four-option
+  vocabulary are as they were; only the unset fallback flipped.
+- Pinned: the player sequence config carries `"order":"reverse"` and
+  feed position 1 plays LAST for an unset feed; the podcast page's
+  dropdown renders `reverse` selected (TestPodcastPlayerOrderControl,
+  replacing the former native pin).