feat(start-work): add auto_commit config option

Add start_work.auto_commit configuration option to allow users to
disable the automatic commit step in the /start-work workflow.

When auto_commit is false:
- STEP 8: COMMIT ATOMIC UNIT is removed from orchestrator reminder
- STEP 9: PROCEED TO NEXT TASK becomes STEP 8

Resolves #2197

assets/oh-my-opencode.schema.json

@@ -3837,6 +3837,19 @@
       },
       "additionalProperties": false
     },
+    "start_work": {
+      "type": "object",
+      "properties": {
+        "auto_commit": {
+          "default": true,
+          "type": "boolean"
+        }
+      },
+      "required": [
+        "auto_commit"
+      ],
+      "additionalProperties": false
+    },
     "_migrations": {
       "type": "array",
       "items": {