nests room: stable reactions overlay + repeatable kind-7 + speaker controls

Reaction-side rework after extended testing on 2026-05-13:

* Promoted users weren't seeing speaker controls in their own
  Amethyst — `StageControlsBar` gates on `isOnStage && ui.onStageNow`
  and `ui.onStageNow` was stuck at false (never reset back to true
  after some earlier path flipped it). Added a LaunchedEffect in
  NestActivityContent that mirrors `isOnStageMe → ui.onStageNow`
  whenever it becomes true, symmetric to the auto-stop effect.

* Reactions overlay sat inside AvatarAndBadges' wrap-content Box,
  so adding/removing the chip shifted the inner Box's centre and
  the role badges drifted. Lifted the overlay out to be a sibling
  of AvatarAndBadges inside the outer fixed-size Box; badges now
  stay anchored regardless of chip presence or animation state.

* Reaction grouping was by `targetPubkey` (NIP-25 p-tag) — emojis
  showed on the speaker being reacted to, not the reactor. Switched
  RoomReactionsAggregator to group by `sourcePubkey`. AudienceGrid
  threads `reactionsByPubkey` so an audience reactor sees their own
  emoji float from their audience-tab avatar too.

* Reaction chip animation: progress was an `Animatable.value` that
  Compose wasn't refreshing in the layout-consuming layer (visible
  bug: chip "blinked" with no movement). Replaced with a manual
  `withFrameNanos` loop writing to a `MutableFloatState` read inside
  a `graphicsLayer { … }` lambda — frame-clock animation that works.
  Each kind-7 is its own chip keyed by event-id (no more
  groupBy-content collapsing same-emoji bursts into one shared chip
  that restarts on every arrival). Chips stack at a fixed-size 30 dp
  Box with the emoji centred, so the X position is invariant under
  glyph width. Multiple concurrent chips overlap at the right-bottom
  corner in a `Box(BottomEnd)` (newest on top) rather than sliding
  leftward in a `Row`.

* Bottom-drawer `RoomReactionPickerSheet` (hard-coded 6 emojis, no
  NIP-30) replaced by a forked `RoomReactionPopup` that reuses
  `ReactionChoicePopupContent` (same NIP-30 custom-emoji support,
  same user-configured reaction set) but with two semantic deviations
  for live audio rooms: empty `toRemove` so all buttons stay
  "fresh", and the click handler signs+broadcasts a fresh kind-7
  template directly instead of going through `Account.reactTo` —
  which delegates to `ReactionAction.reactTo(note, …)` and
  short-circuits on `note.hasReacted(by, reaction)`. The bypass
  lets the user fire the same emoji repeatedly during a moment.

* Chip rendering matches NoteCompose: `RenderReactionContent`
  handles `:shortcode:url` via `InLineIconRenderer` + `CustomEmoji`,
  `"+"`→❤️, `"-"`→👎, anything else as Text.

Tests updated for sender-grouped aggregator semantics.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/viewmodels/RoomReactionsState.kt

@@ -78,9 +78,6 @@ class RoomReactionsAggregator {
     // event id so the same kind-7 from two relays only counts once.
     private val byEventId = LinkedHashMap<String, RoomReaction>()
 
-    /** Stable key for room-wide reactions in the returned map. */
-    private val roomWideKey = ""
-
     /** Apply one reaction and return the post-evict snapshot. */
     fun apply(
         event: ReactionEvent,
@@ -102,13 +99,24 @@ class RoomReactionsAggregator {
      * cadence (typically every second so the floating-up animation
      * frame rate is set by the eviction tick rather than by a
      * per-Composable timer).
+     *
+     * Reactions are grouped by [RoomReaction.sourcePubkey] — the
+     * user who SENT the reaction. The chip floats up from the
+     * reactor's own avatar (matching nostrnests' UX) rather than
+     * from the target speaker's avatar (which would surface the
+     * NIP-25 `p`-tag's "originalAuthor" semantics — useful for
+     * comment threads but confusing in a live audio room, where the
+     * audience expects to see who's reacting, not who's being
+     * reacted to). Room-wide reactions (no `p`-tag at all) still
+     * land under their sender's key, so they show up on the
+     * reactor's avatar just like targeted ones.
      */
     fun evictAndSnapshot(olderThanSec: Long): Map<String, List<RoomReaction>> {
         val it = byEventId.entries.iterator()
         while (it.hasNext()) {
             if (it.next().value.createdAtSec < olderThanSec) it.remove()
         }
-        return byEventId.values.groupBy { it.targetPubkey ?: roomWideKey }
+        return byEventId.values.groupBy { it.sourcePubkey }
     }
 
     /** Whether the aggregator currently holds any unevicted reactions. */