Fix: the combat "freeze on a kill" — camera shake channel + drop the position hold

This is what the operator's report was actually describing, and it was never a CPU
hitch: median frame was 12.2 ms with a kill costing ~15 ms, wave respawn is not a
spike, and enemies carry no PhysicsCollider so corpses never blocked.

Two bugs in PrototypeCameraRig.LateUpdate, both measured with a STATIONARY player
so the ideal camera motion is exactly zero and everything observed is artifact:

1. Shake was integrated by the follow filter. The smoothing ran as
   Lerp(transform.position, desired, k), and transform.position already contained
   last frame's random shake — so the filter treated shake as real positional error
   and corrected only ~9 %/frame. Shake was never subtracted, just slowly lerped out
   while new shake piled on, so in sustained combat the camera random-walked around
   its framing and never settled. One kill left it 0.447 units off-frame and still
   0.199 off 24 frames later. The follow now smooths a _basePos that shake never
   touches; shake is applied only when writing the transform.

2. The position HOLD froze the follow for a fixed number of RENDER frames on every
   kill and heavy hit (2, or 7 on a finisher), making the freeze framerate-dependent
   — 49 ms at 144 fps, 233 ms at 30 fps — and it took its base from
   transform.position, permanently baking that frame's shake in as a 0.283-unit
   single-frame jump. A camera that stops while the world keeps moving reads as a
   hitch, not as crunch. Dropped; impact rides the FOV punch + shake alone
   (operator's call). HitStopMaxFrames / HitStopFreezeEnabled / FinisherHoldFrames
   retire with it, and the three saved feel profiles drop the dead keys.

Worth recording: dropping the hold ALONE measured slightly worse (max deviation
0.653 vs 0.447) — the hold had been partly masking the shake integration. Both
fixes together: deviation returns to 0.000 within a few frames of a kill, mean
deviation 0.038 across the window. The 0.428 peak is now the shake impulse itself,
a transient punch that immediately returns instead of a drift that lingers.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Assets/_Project/Tuning/Profiles/baseline-0720.json

@@ -15,7 +15,6 @@
     "feel": [
         { "k": "MeleeArcIntensity", "v": "0.8" },
         { "k": "MeleeArcBubbles", "v": "6" },
-        { "k": "FinisherHoldFrames", "v": "7" },
         { "k": "MeleeConnectFovKick", "v": "1.1" },
         { "k": "CombatIdleHoldSec", "v": "4" }
     ]

Assets/_Project/Tuning/Profiles/heavy-committed.json

@@ -32,10 +32,6 @@
             "k": "MeleeArcIntensity",
             "v": "0.8"
         },
-        {
-            "k": "FinisherHoldFrames",
-            "v": "7"
-        },
         {
             "k": "MeleeConnectFovKick",
             "v": "1.1"

Assets/_Project/Tuning/Profiles/snappier.json

@@ -11,7 +11,6 @@
     ],
     "feel": [
         { "k": "MeleeArcIntensity", "v": "1.1" },
-        { "k": "FinisherHoldFrames", "v": "4" },
         { "k": "MeleeConnectFovKick", "v": "0.7" }
     ]
 }