feat: support multiple rate limits (#11260)

Added multi-limit support end-to-end by carrying limit_name in
rate-limit snapshots and handling multiple buckets instead of only
codex.
Extended /usage client parsing to consume additional_rate_limits
Updated TUI /status and in-memory state to store/render per-limit
snapshots
Extended app-server rate-limit read response: kept rate_limits and added
rate_limits_by_name.
Adjusted usage-limit error messaging for non-default codex limit buckets

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

@@ -6555,6 +6555,18 @@
             }
           ]
         },
+        "limit_id": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "limit_name": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
         "plan_type": {
           "anyOf": [
             {
@@ -11837,7 +11849,22 @@
         "$schema": "http://json-schema.org/draft-07/schema#",
         "properties": {
           "rateLimits": {
-            "$ref": "#/definitions/v2/RateLimitSnapshot"
+            "allOf": [
+              {
+                "$ref": "#/definitions/v2/RateLimitSnapshot"
+              }
+            ],
+            "description": "Backward-compatible single-bucket view; mirrors the historical payload."
+          },
+          "rateLimitsByLimitId": {
+            "additionalProperties": {
+              "$ref": "#/definitions/v2/RateLimitSnapshot"
+            },
+            "description": "Multi-bucket view keyed by metered `limit_id` (for example, `codex`).",
+            "type": [
+              "object",
+              "null"
+            ]
           }
         },
         "required": [
@@ -12852,6 +12879,18 @@
               }
             ]
           },
+          "limitId": {
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "limitName": {
+            "type": [
+              "string",
+              "null"
+            ]
+          },
           "planType": {
             "anyOf": [
               {