feat: add spindle direction selection contract

shared/machine/fullum-alpha.capabilities.v1.json

@@ -107,6 +107,16 @@
       "name": "force_setpoint_n",
       "unit": "see docs/05-telemetry-channel-spec-v1.md",
       "sample_rate_hz": 100
+    },
+    {
+      "name": "spindle_direction_setpoint",
+      "unit": "enum(cw|ccw)",
+      "sample_rate_hz": 10
+    },
+    {
+      "name": "spindle_direction_actual",
+      "unit": "enum(cw|ccw)",
+      "sample_rate_hz": 10
     }
   ],
   "safety_limits": {
@@ -126,5 +136,9 @@
     "Final ODrive runtime interface and command scaling.",
     "Final SV2A-2150 torque/current command scaling and Iq monitor mapping.",
     "Final safety relay model and wiring details."
+  ],
+  "supported_spindle_directions": [
+    "cw",
+    "ccw"
   ]
 }