feat(podcasts): queue context source + player order control — item 2.2

Foundation rule R2 (§10): the queue context is the only queue, and
every producer emits the same shape. PodcastSequenceContext gains
source (feed|collection), feed_id, and order; the feed producer sets
them now — the collection producer (2.3) slots into the same shape
without the player ever special-casing beyond showing/hiding controls.

The player header gains the FEED-mode order control next to the
"Ep N/M" counter: a dropdown (native/reverse/oldest/newest) plus a
one-click reverse button. Both PUT the existing per-user feed order
override — the SAME state the feed page writes, so flipping it in the
player updates the feed page's dropdown too. The control renders only
when source=feed: a collection queue's order is curated content
(R1), never a listening preference. Behavior is hx-put +
hx-swap="none" (response discarded) with a module-level
htmx:afterRequest listener in audio.ts reloading the page — the
server re-renders prev/next/index in the new order; templ decides
what it looks like, JS only triggers the round trip (CSP-clean, no
inline handlers).

Pinned by TestPodcastPlayerOrderControl: the config JSON carries
source/feed_id/order/episode_index; the control renders feed-mode;
an order override re-renders with the dropdown reflecting it (data-
json pins must match templ's " attribute escaping).

templates/types.go

@@ -327,6 +327,19 @@ type PodcastSequenceContext struct {
 	PrevURL   string `json:"prev_url,omitempty"`
 	NextURL   string `json:"next_url,omitempty"`
 	NextTitle string `json:"next_title,omitempty"`
+	// Source is the queue's owner (§10 R2: every producer emits the
+	// same shape): "feed" = the feed's effective order (per-user
+	// override applied), "collection" = an ordered Up Next collection
+	// (2.3). The player shows/hides controls by source — the order
+	// control is FEED-mode only, because a collection's order is
+	// curated content, not a listening preference.
+	Source string `json:"source,omitempty"`
+	// Feed-mode fields: FeedID powers the player's order control (it
+	// PUTs /api/podcasts/feeds/:id/order — the same per-user override
+	// the feed page writes); Order is the resolved current value that
+	// the dropdown reflects. Empty in collection mode.
+	FeedID string `json:"feed_id,omitempty"`
+	Order  string `json:"order,omitempty"`
 	// EpisodeIndex/IndexTotal render the "Ep N of M" indicator (D7).
 	EpisodeIndex int `json:"episode_index,omitempty"`
 	IndexTotal   int `json:"index_total,omitempty"`