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.

internal/router/podcast_page.go

@@ -381,6 +381,13 @@ func buildPodcastDetailData(c *echo.Context, cfg *Config, user templates.User, f
 }
 
 // podcastOrderForFeed reads the caller's order override (D5).
+//
+// The UNSET default is "reverse" (2026-11-01 user request): the platform
+// is audiobook-first and feed document order runs newest-first, so
+// native starts a book at its LAST chapter. This is the same per-feed
+// setting the Order dropdown shows — page list, player chain, and
+// download queue all resolve through it. Stored overrides are untouched:
+// anyone who picked an order keeps exactly what they picked.
 func podcastOrderForFeed(cfg *Config, c *echo.Context, feedID string) string {
 	user := handlers.MustGetAuthenticatedUser(c)
 	row, err := cfg.Queries.GetUserSettingByKey(c.Request().Context(), database.GetUserSettingByKeyParams{
@@ -388,16 +395,16 @@ func podcastOrderForFeed(cfg *Config, c *echo.Context, feedID string) string {
 		SettingKey: "podcast_order:" + feedID,
 	})
 	if err != nil {
-		return "native"
+		return "reverse"
 	}
 	var v struct {
 		Order string `json:"order"`
 	}
 	if err := json.Unmarshal(row, &v); err != nil {
-		return "native"
+		return "reverse"
 	}
 	if !services.ValidPodcastEpisodeOrder(v.Order) {
-		return "native"
+		return "reverse"
 	}
 	return v.Order
 }