feat(lint,player): fast-capture lint rule + player media sync (#1921)

* feat(engine): drawElementImage capture service

* feat(engine): 3D projection + compositor-effect risk gate

* fix(engine): gate filter drop-shadow wherever blur gates (review)

detectCssEffectRisk documented drop-shadow as a ~29dB damage case but only
detected blur( in its three scan paths — a drop-shadow comp stayed on the
fast path despite the gate's own correctness contract. Detect drop-shadow(
in computed styles, stylesheet rules, and GSAP tween vars, pinned by a
focused test that runs the real page-side closure against a DOM shim
(computed / stylesheet / tween coverage + blur regression + effect-free
null).

Addresses miguel-heygen's blocker on #1918.

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

* feat(engine): frame-capture core — fast-capture routing, worker-encode, dedup extension

# Conflicts:
#	packages/engine/src/services/screenshotService.ts

* fix(engine): document HF_FORCE_DRAWELEMENT as diagnostic-only; make armStaticDedup idempotent (review)

Addresses miguel-heygen's blockers on #1919:

- HF_FORCE_DRAWELEMENT promoted from a stale "SCRATCH/Uncommitted" comment to
  a documented diagnostic flag: it exists for upstream-Chromium repro work
  (gate-vs-API isolation, crbug 521861819 149-vs-151) and R&D on gated effect
  classes; renders under it may be damaged BY DESIGN since it bypasses gates
  whose thresholds encode measured damage. Never production; the safety-net
  blank guard also stands down under it so diagnostic frames arrive unmodified.
- armStaticDedup is now idempotent: the drawElement init path arms dedup
  before canvas injection, then initializeSession called it again — the
  second run overwrote the armed state with skipReason="capture_mode"
  (captureMode is "drawelement" by then), producing contradictory telemetry
  (armed frames + a skip reason), and re-ran the verification seeks on the
  fallback path. It now no-ops once staticFrames or a skip decision exists.

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

* feat(producer): fast-capture render stages + remote bg-image localizer

* feat(lint,player): fast-capture lint rule + player media sync

---------

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

packages/player/src/controls.ts

@@ -10,6 +10,10 @@ export interface ControlsCallbacks {
   onPlay: () => void;
   onPause: () => void;
   onSeek: (fraction: number) => void;
+  /** Scrub drag started (mousedown/touchstart on the scrubber). */
+  onScrubStart?: () => void;
+  /** Scrub drag ended (mouseup/touchend). */
+  onScrubEnd?: () => void;
   onSpeedChange: (speed: number) => void;
   onMuteToggle: () => void;
   onVolumeChange: (volume: number) => void;
@@ -293,13 +297,17 @@ export function createControls(
   scrubber.addEventListener("mousedown", (e) => {
     e.stopPropagation();
     scrubbing = true;
+    callbacks.onScrubStart?.();
     handleScrubAt(e.clientX);
   });
   const onMouseMove = (e: MouseEvent) => {
     if (scrubbing) handleScrubAt(e.clientX);
   };
   const onMouseUp = () => {
-    scrubbing = false;
+    if (scrubbing) {
+      scrubbing = false;
+      callbacks.onScrubEnd?.();
+    }
   };
   document.addEventListener("mousemove", onMouseMove);
   document.addEventListener("mouseup", onMouseUp);
@@ -308,6 +316,7 @@ export function createControls(
     "touchstart",
     (e) => {
       scrubbing = true;
+      callbacks.onScrubStart?.();
       const touch = e.touches[0];
       if (touch) handleScrubAt(touch.clientX);
     },
@@ -320,7 +329,10 @@ export function createControls(
     }
   };
   const onTouchEnd = () => {
-    scrubbing = false;
+    if (scrubbing) {
+      scrubbing = false;
+      callbacks.onScrubEnd?.();
+    }
   };
   document.addEventListener("touchmove", onTouchMove, { passive: true });
   document.addEventListener("touchend", onTouchEnd);