feat(V&V): Updated to FEA CSV format + real M2 mesh injection

- Output now matches WFE_from_CSV_OPD format: ,X,Y,Z,DX,DY,DZ (meters)
- Suite regenerated using real M2 mesh (357 nodes, 308mm diameter)
- All 14 clean test cases: PASS (0.000 nm error)
- 3 noisy cases: expected FAIL due to low node count amplifying noise
- Added --inject mode to use real FEA mesh geometry
- Added lateral displacement test case

tools/validation_suite/many_modes_truth.json

@@ -95,10 +95,16 @@
     "49": "Z(9,+3)",
     "50": "Z(9,-5)"
   },
-  "n_points": 118572,
-  "diameter_mm": 1200.0,
-  "rms_nm_clean": 16.40426082558852,
-  "rms_nm_with_noise": 16.40426082558852,
+  "n_points": 357,
+  "diameter_mm": 308.4492626330409,
+  "rms_nm_clean": 14.718241472214698,
+  "rms_nm_with_noise": 14.718241472214698,
   "noise_rms_nm": 0.0,
-  "seed": 42
+  "include_lateral": false,
+  "seed": 42,
+  "units": {
+    "positions": "meters",
+    "displacements": "meters",
+    "coefficients": "nanometers"
+  }
 }