fix(ui): scope hand-tracking activation + clean MissionNotification video branch

- HandTrackingProvider: drop the physics-mode auto-activation that turned
  the camera/MediaPipe pipeline on whenever any interactable was nearby
  (e.g. walking near the ebike to mount it). Hand tracking is now gated
  *only* by the active repair-mission step (inspected, repairing,
  reassembling, done). When testing in TestMap, set
  mainState=ebike + currentStep=inspected via the GameStateDebugPanel.
- MissionNotification: video branch no longer inherits the CRT-style
  enter/scan/flicker/sepia animations applied to the PNG branch via
  index.css. The webm assets already animate themselves, so the wrapping
  container is rendered with inline styles only (clip-path silhouette
  preserved, but no .__image-wrap::before scan line, no .__image flicker
  filter, no parent enter animation, no drop-shadow).

src/components/ui/MissionNotification.tsx

@@ -6,6 +6,12 @@ import type { RepairMissionId } from "@/types/gameplay/repairMission";
 // <video> element renders at the wrong dimensions and shifts the layout.
 const NOTIFICATION_ASPECT_RATIO = "589 / 211";
 
+// Same clip-path as `.mission-notification__image-wrap` in index.css. Inlined
+// here so the video branch can re-use the silhouette without inheriting the
+// scan-line `::before` and CRT animations applied to the PNG branch.
+const NOTIFICATION_CLIP_PATH =
+  "polygon(0 0, 100% 0, 100% 69%, 88% 100%, 0 100%)";
+
 interface MissionNotificationProps {
   mission?: RepairMissionId;
   imagePath?: string;
@@ -24,14 +30,34 @@ export function MissionNotification({
   return (
     <div
       className={`mission-notification${visible ? "" : " mission-notification--hidden"}`}
+      // Webm assets already animate themselves; suppress the CRT entrance
+      // flicker + drop-shadow that index.css applies to all .mission-notification
+      // nodes so the video plays in a clean container.
+      style={
+        isVideo
+          ? {
+              animation: "none",
+              filter: "none",
+            }
+          : undefined
+      }
       aria-live="polite"
     >
-      <div className="mission-notification__glow" />
+      {isVideo ? null : <div className="mission-notification__glow" />}
-      <span className="mission-notification__image-wrap">
       {isVideo ? (
-          <video
+        <span
-            className="mission-notification__image"
           style={{
+            position: "relative",
+            display: "block",
+            overflow: "hidden",
+            clipPath: NOTIFICATION_CLIP_PATH,
+          }}
+        >
+          <video
+            style={{
+              display: "block",
+              width: "100%",
+              height: "auto",
               aspectRatio: NOTIFICATION_ASPECT_RATIO,
               objectFit: "cover",
             }}
@@ -43,14 +69,16 @@ export function MissionNotification({
             playsInline
             preload="auto"
           />
+        </span>
       ) : (
+        <span className="mission-notification__image-wrap">
           <img
             className="mission-notification__image"
             src={src}
             alt="Nouvel objectif de mission"
           />
-        )}
         </span>
+      )}
     </div>
   );
 }

src/providers/gameplay/HandTrackingProvider.tsx

@@ -1,9 +1,7 @@
 import type { ReactNode } from "react";
 import { useEffect, useState } from "react";
 import { HAND_TRACKING_LINGER_MS } from "@/data/handTrackingConfig";
-import { useSceneMode } from "@/hooks/debug/useSceneMode";
 import { useDebugStore } from "@/hooks/debug/useDebugStore";
-import { useInteraction } from "@/hooks/interaction/useInteraction";
 import {
   HAND_TRACKING_IDLE_SNAPSHOT,
   HandTrackingContext,
@@ -25,8 +23,14 @@ export function HandTrackingProvider({
 }: {
   children: ReactNode;
 }): React.JSX.Element {
-  const sceneMode = useSceneMode();
+  // Hand tracking is gated *only* by the active repair-mission step. We
-  const repairNeedsHands = useGameStore((state) => {
+  // intentionally do NOT activate it from generic interactable proximity
+  // (e.g. standing next to the ebike to mount it) — that previously caused
+  // hand tracking to spin up around any interactable in the physics
+  // (TestMap) scene mode, even though the player wasn't in a step that
+  // actually uses hands. Use the GameStateDebugPanel to set
+  // mainState=ebike + currentStep=inspected when testing in TestMap.
+  const requested = useGameStore((state) => {
     switch (state.mainState) {
       case "ebike":
         return REPAIR_HAND_TRACKING_STEPS.has(state.ebike.currentStep);
@@ -39,10 +43,6 @@ export function HandTrackingProvider({
         return false;
     }
   });
-  const { nearby, holding, handHolding } = useInteraction();
-  const requested =
-    repairNeedsHands ||
-    (sceneMode === "physics" && (nearby || holding || handHolding));
 
   // Keep the runtime active a little after `requested` turns off so
   // MediaPipe has time to initialize the webcam + model + first frame