Better handling for specific 401 errors

For example, "account disabled".

Sentry Issue: [MCP-SERVER-EHX](https://sentry.sentry.io/issues/6806092065/?referrer=github_integration)

```
Error: API request failed: 401 Unauthorized
{"detail":{"code":"member-disabled-over-limit","message":"Organization over member limit","extra":{"next":"/organizations/wagwalking/disabled-member/"}}}
at SentryApiService.request (../../../mcp-server/dist/client-C7afKNhY.js:185:10)
at SentryApiService.requestJSON (../../../mcp-server/dist/client-C7afKNhY.js:225:20)
at SentryApiService.listTags (../../../mcp-server/dist/client-C7afKNhY.js:670:16)
at discoverDatasetFields (../../../mcp-server/dist/dataset-fields-yzLxqctK.js:11:15)
at Object.execute (../../../mcp-server/dist/utils-BTr7q5k6.js:31:11)
...
(5 additional frame(s) were not displayed)

AI_ToolExecutionError: Error executing tool issueFields: API request failed: 401 Unauthorized
{"detail":{"code":"member-disabled-over-limit","message":"Organization over member limit","extra":{"next":"/organizations/wagwalking/disabled-member/"}}}
at Promise.all (index 1)
at callEmbeddedAgent (../../../mcp-server/dist/callEmbeddedAgent-Ckbl7BOC.js:15:17)
at searchIssuesAgent (../../../mcp-server/dist/agent-CZ5wN-ur.js:25:9)
at withApiErrorHandling (../../../mcp-server/dist/api-CrrLDuiK.js:60:10)
...
(5 additional frame(s) were not displayed)
```