feat(audio-rooms): "Listen to recording" CTA for closed rooms

Wire MeetingSpaceEvent's existing RecordingTag into the
note-view renderer. Closed rooms (status=CLOSED) that ship a
`["recording", url]` tag get an OutlinedButton that hands the
URL to the system media player via ACTION_VIEW — most users have
a podcast / audio app registered for HTTPS audio URLs.

Live and scheduled rooms keep the Join button. Closed rooms
without a recording render no CTA — there's nothing to enter.

Adds:
  * MeetingSpaceEvent.recording() accessor
  * TagArrayBuilder<MeetingSpaceEvent>.recording(url) DSL builder
  * ListenToRecordingButton composable in the note renderer

Note: nostrnests' moq-lite refactor dropped the LiveKit-era
recording HTTP surface, but the kind-30312 `recording` tag is
still spec-allowed and individual hosts can populate it via
out-of-band capture. This commit makes Amethyst the receiving
end for any host who does.

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip53LiveActivities/meetingSpaces/MeetingSpaceEvent.kt

@@ -93,6 +93,15 @@ class MeetingSpaceEvent(
      */
     fun font() = tags.firstNotNullOfOrNull(com.vitorpamplona.quartz.nip53LiveActivities.meetingSpaces.tags.FontTag::parse)
 
+    /**
+     * Optional URL to a post-room recording. Hosts that record a
+     * room re-publish the kind-30312 with `status=closed` and
+     * `["recording", url]` so audience members who missed the live
+     * session can listen back. Returns null when no recording is
+     * available.
+     */
+    fun recording() = tags.firstNotNullOfOrNull(com.vitorpamplona.quartz.nip53LiveActivities.meetingSpaces.tags.RecordingTag::parse)
+
     /**
      * Scheduled start time as unix seconds, only meaningful when
      * [status] is [StatusTag.STATUS.PLANNED]. Returns null on

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip53LiveActivities/meetingSpaces/TagArrayBuilderExt.kt

@@ -61,6 +61,12 @@ fun TagArrayBuilder<MeetingSpaceEvent>.font(
         .assemble(family, url),
 )
 
+fun TagArrayBuilder<MeetingSpaceEvent>.recording(url: String) =
+    addUnique(
+        com.vitorpamplona.quartz.nip53LiveActivities.meetingSpaces.tags.RecordingTag
+            .assemble(url),
+    )
+
 fun TagArrayBuilder<MeetingSpaceEvent>.relays(urls: List<NormalizedRelayUrl>) = addUnique(RelayListTag.assemble(urls))
 
 fun TagArrayBuilder<MeetingSpaceEvent>.participant(