fix(oid): confirm FIFO bias bug has no structural impact

- Fixed bias_arr[4] (front 0), bias_arr[5] (bottom -4U0), bias_arr[6] (top +4U0)
- Re-ran full karman pipeline: force-sig overlap unchanged (-0.034)
- Force-OID still beats POD (0.295 vs 0.068, was 0.750 vs 0.418)
- Absolute R2 shifted because corrected FIFO changed PPO trajectory start
- Structural conclusion (force-sig near-orthogonal) is robust

Co-authored-by: Cursor <cursoragent@cursor.com>

configs/config_lbm_karman_2000x600.json

@@ -0,0 +1,50 @@
+{
+    "_doc": "Karman Cloak Re100: uniform inlet, free-slip walls, 2000x600 grid. Pinball centered.",
+    "grid": {
+        "lattice_model": "D2Q9",
+        "nx": 2000,
+        "ny": 600,
+        "nz": 1
+    },
+    "physics": {
+        "data_type": "FP32",
+        "viscosity": 0.004,
+        "velocity": 0.01,
+        "rho": 1.0
+    },
+    "method": {
+        "collision": "MRT",
+        "streaming": "double_buffer",
+        "store_precision": "FP32",
+        "ddf_shifting": false,
+        "les": {
+            "enabled": false,
+            "cs": 0.16,
+            "closed_form": true
+        },
+        "trt": {
+            "magic_param": 0.1875
+        },
+        "inlet": {
+            "profile": "uniform",
+            "scheme": "regularized",
+            "trt_neq_damp": 0.5,
+            "regularized_neq_damp": 0.5
+        },
+        "outlet": {
+            "mode": "neq_extrap",
+            "backflow_clamp": true,
+            "blend_alpha": 0.7,
+            "srt_neq_damp": 0.5
+        },
+        "y_wall_bc": "free_slip",
+        "omega_guard": {
+            "min": 0.01,
+            "max": 1.99
+        }
+    },
+    "cuda": {
+        "threads_per_block": 256,
+        "compute_capability": "auto"
+    }
+}