feat(studio): group rows in the timeline, and a split disclosure (#3286)

* feat(core,studio): the character presets pitch shift unlocks

Chipmunk, Giant, and Monster ship as presets on the pitchshift worklet
P1 added: Chipmunk pitches up and adds sparkle, Giant pitches down with
weight and a compressor to hold the extra low end together, Monster pitches
down further with saturation growl and a close, tight reverb. Every param
verified against the live effect registry rather than sketched — the
compressor/reverb/saturate/shelf keys all match exactly.

Each gets its own title treatment (font, size, tracking, hue) so the FX
rack's per-preset styling coverage and hue-distance/background-uniqueness
tests extend cleanly to the three new entries, and complaint-line copy in
the non-voice vocabulary the audit test enforces (no speech words — "Giant"
over CapCut's "Deep Voice", as the design doc records).

Updates plans/audio-fx-presets.md's two limits paragraphs to record that
pitch shift landed and this half of the character list now ships; Robot and
Alien stay out of scope (ring modulation, still unbuilt).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

* feat(core): the audio group model — element, membership, helpers

Introduces <hf-audio-group> and data-audio-group as the group model B2–B7
and C1 build on: a non-rendering group element carries a label and (later)
an FX chain, membership lives on the member's own data-audio-group
attribute rather than DOM nesting, so a track removed from the document
simply drops out of the group on the next resolve — nothing dangles.
Groups do not nest: data-audio-group on the group element itself is
ignored. A group with members but no <hf-audio-group> element still
resolves, label falling back to the id, so hand-authored HTML degrades
gracefully. Audio only in v1 — video members are ignored.

Parse-only: nothing routes or sums audio yet (B3/B4). Adds the
audio-groups canary at percentage: 0 gating the future Studio UI; the
element and attribute parse and play regardless of enrollment.

Verified rather than assumed per this plan's standing rule: the timeline's
clip-collection selector ([data-start], [data-track-index],
[data-composition-id], video, audio, img) already excludes the group
element with zero changes, and no lint rule flags unknown elements or
data-* attributes, so neither needed touching — confirmed by grep and by
running `hyperframes lint` against a fixture containing the element (0
findings referencing it). The step doc's suggested display:none injection
point (an existing base stylesheet in the runtime) does not exist in this
codebase; skipped rather than inventing new infrastructure, since an empty,
childless custom element already renders as a zero-size inline box with no
visible output — the same reasoning the lint check above confirms
empirically.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

* feat(studio): group rows in the timeline, and a split disclosure

A group renders as its own row with member rows beneath it, and disclosure
splits into two independent controls: caret shows/hides a group's member
rows (structural), `∿` shows/hides any row's automation-lane rows. Plain
tracks lose their caret (nothing to disclose structurally) and keep only
`∿`. `expandedClipIds` keeps its existing keyframe-lane-state job;
`expandedGroupIds`/`expandedLaneOwnerIds` are new, independent sets.

Groups get a real position in the row/geometry pipeline rather than a
visual-only overlay: `useTimelineTrackDerivations` re-emits a group's member
tracks contiguously under a synthetic fractional anchor key
(firstMember - 0.5, the same fractional-key convention sub-composition
expansion already uses), so `rowGeometry`/keyboard-nav/virtualization treat
a group row as a first-class row without widening their key type away from
number. `TimelineLogicalRow.level` widens `1 | 2` to `1 | 2 | 3` (group /
member-under-group / lane), lanes always `owner.level + 1`.

All of it — grouped row emission, the header, the new expansion state — is
gated behind `isCanaryEnabled("audio-groups")`; disabled, `groups` resolves
empty and every new code path no-ops. `TimelineElement.audioGroup` (+
`audioGroupLabel`, resolved once per document via `resolveAudioGroups` from
B1) is parsed unconditionally, mirroring how `hidden`/`fxChain` already
flow DOM → manifest → TimelineElement — inert without the canary.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>

packages/studio/src/hooks/useMusicBeatAnalysis.ts

@@ -4,6 +4,8 @@ import { resolveBeatSourceTrack } from "../utils/timelineInspector";
 import { analyzeMusicFromUrl } from "@hyperframes/core/beats";
 import { useFileManagerContextOptional } from "../contexts/FileManagerContext";
 import { mergeUserBeats } from "../utils/beatEditing";
+import { getTimelineElementIndexes } from "../player/lib/timelineElementIndexes";
+import { remapBeatAnalysisToComposition } from "../utils/beatEditActions";
 import {
   audioRelPathForSrc,
   beatFilePathForSrc,
@@ -90,6 +92,17 @@ async function loadBeatAnalysis(
   }
 }
 
+/** The current beat analysis, remapped onto the composition's edited beat grid. */
+export function useAdjustedBeatAnalysis() {
+  const beatAnalysis = usePlayerStore((s) => s.beatAnalysis);
+  const musicElement = usePlayerStore((s) => getTimelineElementIndexes(s.elements).musicElement);
+  const beatEdits = usePlayerStore((s) => s.beatEdits);
+  return useMemo(
+    () => remapBeatAnalysisToComposition(beatAnalysis, musicElement, beatEdits),
+    [beatAnalysis, musicElement, beatEdits],
+  );
+}
+
 export function useMusicBeatAnalysis(): void {
   const elements = usePlayerStore((s) => s.elements);
   const setBeatAnalysis = usePlayerStore((s) => s.setBeatAnalysis);