Show estimated thread usage in /status (#38281)

## What changed

- Extend `account/usage/read` with an optional `threadId` request and a
  backward-compatible `threadUsage` response containing estimated credits,
  optional USD cost, and model, reasoning, speed, and token breakdowns.
- Fetch thread usage for eligible Business and Enterprise plans when `/status`
  is opened, then update the rendered status card asynchronously.
- Preserve terminal scrollback when replacing a visible status-card tail, and
  append a refreshed card when the original tail can no longer be updated.

## Testing

- Add app-server coverage for authentication, canonical thread IDs,
  unavailable billing routes, and malformed IDs.
- Add TUI coverage for usage formatting, stale responses, retries, history
  updates, terminal reflow, and scrollback preservation.

GitOrigin-RevId: 49300914b3fba917c0f08e8595363e04e5ba6d37

codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json

@@ -2062,7 +2062,14 @@
               "type": "string"
             },
             "params": {
-              "type": "null"
+              "anyOf": [
+                {
+                  "$ref": "#/definitions/v2/GetAccountTokenUsageParams"
+                },
+                {
+                  "type": "null"
+                }
+              ]
             }
           },
           "required": [
@@ -11377,6 +11384,18 @@
         "title": "GetAccountResponse",
         "type": "object"
       },
+      "GetAccountTokenUsageParams": {
+        "properties": {
+          "threadId": {
+            "description": "When present, read estimated usage for this thread instead of account-wide token activity.",
+            "type": [
+              "string",
+              "null"
+            ]
+          }
+        },
+        "type": "object"
+      },
       "GetAccountTokenUsageResponse": {
         "$schema": "http://json-schema.org/draft-07/schema#",
         "properties": {
@@ -11391,6 +11410,18 @@
           },
           "summary": {
             "$ref": "#/definitions/v2/AccountTokenUsageSummary"
+          },
+          "threadUsage": {
+            "anyOf": [
+              {
+                "$ref": "#/definitions/v2/ThreadUsage"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "default": null,
+            "description": "Estimated usage when a thread was requested and its billing route is available."
           }
         },
         "required": [
@@ -14253,6 +14284,18 @@
         ],
         "type": "string"
       },
+      "NullableGetAccountTokenUsageParams": {
+        "$schema": "http://json-schema.org/draft-07/schema#",
+        "anyOf": [
+          {
+            "$ref": "#/definitions/v2/GetAccountTokenUsageParams"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "title": "Nullable_GetAccountTokenUsageParams"
+      },
       "OverriddenMetadata": {
         "properties": {
           "effectiveValue": true,
@@ -21817,6 +21860,101 @@
         ],
         "type": "string"
       },
+      "ThreadUsage": {
+        "properties": {
+          "estimatedUsageCreditsMicros": {
+            "format": "int64",
+            "type": "integer"
+          },
+          "estimatedUsageUsdMicros": {
+            "format": "int64",
+            "type": [
+              "integer",
+              "null"
+            ]
+          },
+          "groups": {
+            "items": {
+              "$ref": "#/definitions/v2/ThreadUsageBreakdownGroup"
+            },
+            "type": "array"
+          },
+          "threadId": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "estimatedUsageCreditsMicros",
+          "groups",
+          "threadId"
+        ],
+        "type": "object"
+      },
+      "ThreadUsageBreakdownGroup": {
+        "properties": {
+          "cachedInputTokens": {
+            "format": "int64",
+            "type": [
+              "integer",
+              "null"
+            ]
+          },
+          "estimatedUsageCreditsMicros": {
+            "format": "int64",
+            "type": "integer"
+          },
+          "inputTokens": {
+            "format": "int64",
+            "type": [
+              "integer",
+              "null"
+            ]
+          },
+          "model": {
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "netNewInputTokens": {
+            "format": "int64",
+            "type": [
+              "integer",
+              "null"
+            ]
+          },
+          "outputTokens": {
+            "format": "int64",
+            "type": [
+              "integer",
+              "null"
+            ]
+          },
+          "reasoningEffort": {
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "speed": {
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "totalTokens": {
+            "format": "int64",
+            "type": [
+              "integer",
+              "null"
+            ]
+          }
+        },
+        "required": [
+          "estimatedUsageCreditsMicros"
+        ],
+        "type": "object"
+      },
       "TokenUsageBreakdown": {
         "properties": {
           "cacheWriteInputTokens": {