chore: SR pipeline restructuring + DRL training infrastructure

SR_analysis restructured:
- Stage 1/2/3/4 unified pipeline with per-stage docs
- Old scripts/sindy/validate moved to old/archive
- Results reorganized: formulas/validations/figures with scene_registry.json
- Added diagnostic plots and PIPELINE.md

drl_pinball/train:
- New illusion training pipeline: env_illusion.py, train_illusion.py
- Cross-Re transfer: crossre_transfer.sh, extend_transfer.sh
- Calibration data: 0.75L/1L/1.5L/2L + re60/re100/re200/re400
- Launch scripts for multi-GPU training

Cleaned 100+ intermediate/dead files from SR_analysis.

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

configs/config_lbm_karman_2000x600_re50.json

@@ -1,50 +0,0 @@
-{
-    "_doc": "Karman Cloak Re50: uniform inlet, free-slip walls, 2000x600 grid. Pinball centered.",
-    "grid": {
-        "lattice_model": "D2Q9",
-        "nx": 2000,
-        "ny": 600,
-        "nz": 1
-    },
-    "physics": {
-        "data_type": "FP32",
-        "viscosity": 0.008,
-        "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"
-    }
-}