feat(review): flag handles in the review player (metadata only)

Renders run 8 frames past the cut at each end. Directors were flagging
glitches in unfixed handles as shot problems, so the player now marks
them — without trimming or burning anything into the EXRs/MOV/MP4.

- Version.handleHead/handleTail/pictureStartFrame, Export.handleHead/
  handleTail; migration backfills pipeline exports and their preview
  versions from the manifest's handleFrames (else 8)
- AE panel: "Includes handles [8] frames each end" -> manifest.review;
  older manifests fall back to source.handleFrames
- finalize copies handles onto the Version; worker 1.6.4 reports the
  head slate length (pictureStartSeconds), else the player infers it
  as MP4 frames - EXR frameCount
- Player: hatched HANDLE / SLATE regions and cut marks on the timeline,
  "HEAD/TAIL HANDLE · NOT IN EDIT" overlay on handle frames, HANDLE badge
  on notes, "Edit range only" toggle (default on in the client portal)
- Staff Handles editor on the review page for manual uploads/corrections

Also fixes two player bugs found while testing: timeToFrame floored
float error (every seek landed a frame early), and J/reverse never ran
(the keyboard effect's cleanup stopped it on the next render).

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

hooks/use-review-player.ts

@@ -1,6 +1,7 @@
 import { create } from "zustand";
 import type { AnnotationTool } from "@/types";
 import { ASPECT_OFF, type BlankingMode } from "@/lib/aspect-overlays";
+import type { EditRange } from "@/lib/handles";
 
 interface ReviewPlayerStore {
   // Playback
@@ -28,6 +29,11 @@ interface ReviewPlayerStore {
   fps: number;
   totalFrames: number;
 
+  // Handles — where the cut sits in the media (null: no handles marked), and
+  // whether playback keeps to it. Viewing aids only; the media is untouched.
+  editRange: EditRange | null;
+  editRangeOnly: boolean;
+
   // Actions
   setPlaying: (playing: boolean) => void;
   setCurrentFrame: (frame: number) => void;
@@ -46,6 +52,8 @@ interface ReviewPlayerStore {
   setBlankingMode: (mode: BlankingMode) => void;
   setFps: (fps: number) => void;
   setTotalFrames: (frames: number) => void;
+  setEditRange: (range: EditRange | null) => void;
+  setEditRangeOnly: (on: boolean) => void;
   reset: () => void;
 }
 
@@ -67,6 +75,8 @@ const initialState = {
   blankingMode: "solid" as BlankingMode,
   fps: 24,
   totalFrames: 0,
+  editRange: null as EditRange | null,
+  editRangeOnly: false,
 };
 
 export const useReviewStore = create<ReviewPlayerStore>((set) => ({
@@ -88,5 +98,7 @@ export const useReviewStore = create<ReviewPlayerStore>((set) => ({
   setBlankingMode: (blankingMode) => set({ blankingMode }),
   setFps: (fps) => set({ fps }),
   setTotalFrames: (totalFrames) => set({ totalFrames }),
+  setEditRange: (editRange) => set({ editRange }),
+  setEditRangeOnly: (editRangeOnly) => set({ editRangeOnly }),
   reset: () => set(initialState),
 }));