Support SSH-backed exec-server routing

- add exec_server.command config plumbing and propagate it through codex exec session startup
- fix remote shell path/cwd translation and preserve early stdout for short exec-server commands

Co-authored-by: Codex <noreply@openai.com>

codex-rs/core/config.schema.json

@@ -383,6 +383,10 @@
             "enable_request_compression": {
               "type": "boolean"
             },
+            "exec_permission_approvals": {
+            "experimental_exec_server": {
+              "type": "boolean"
+            },
             "exec_permission_approvals": {
               "type": "boolean"
             },
@@ -606,6 +610,18 @@
       },
       "type": "object"
     },
+    "ExecServerConfigToml": {
+      "additionalProperties": false,
+      "properties": {
+        "command": {
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        }
+      },
+      "type": "object"
+    },
     "FeedbackConfigToml": {
       "additionalProperties": false,
       "properties": {
@@ -1850,6 +1866,15 @@
       "description": "When true, disables burst-paste detection for typed input entirely. All characters are inserted as they are received, and no buffering or placeholder replacement will occur for fast keypress bursts.",
       "type": "boolean"
     },
+    "exec_server": {
+      "allOf": [
+        {
+          "$ref": "#/definitions/ExecServerConfigToml"
+        }
+      ],
+      "default": null,
+      "description": "Optional command vector used to launch the experimental exec-server."
+    },
     "experimental_compact_prompt_file": {
       "$ref": "#/definitions/AbsolutePathBuf"
     },
@@ -1935,6 +1960,10 @@
         "enable_request_compression": {
           "type": "boolean"
         },
+        "exec_permission_approvals": {
+        "experimental_exec_server": {
+          "type": "boolean"
+        },
         "exec_permission_approvals": {
           "type": "boolean"
         },
@@ -2469,4 +2498,4 @@
   },
   "title": "ConfigToml",
   "type": "object"
-}
+}