[Bug] Model Alias Not Supported in Custom Slash Command Configuration

Bug Description
When using model: in custom slash commands, it doesn't support aliases (sonnet, opus, etc) model names, only exact API model names are supported.

Environment Info

• Platform: linux
• Terminal: vscode
• Version: 1.0.120
• Feedback ID: 9771a916-2c8f-452f-bd3b-96c7ac8b3889

Errors

[{"error":"Error: 404 {\"type\":\"error\",\"error\":{\"type\":\"not_found_error\",\"message\":\"model: sonnet\"},\"request_id\":\"req_011CTS8mGz3Wo5D2Zzyp2L3M\"}\n    at i9.generate (file:///usr/lib/node_modules/@anthropic-ai/claude-code/cli.js:992:2516)\n    at IP.makeStatusError (file:///usr/lib/node_modules/@anthropic-ai/claude-code/cli.js:1009:2131)\n    at IP.makeRequest (file:///usr/lib/node_modules/@anthropic-ai/claude-code/cli.js:1009:5344)\n    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)\n    at async RJB.ZI1.showErrors (file:///usr/lib/node_modules/@anthropic-ai/claude-code/cli.js:1919:29907)\n    at async ZI1 (file:///usr/lib/node_modules/@anthropic-ai/claude-code/cli.js:1919:18054)\n    at async RJB (file:///usr/lib/node_modules/@anthropic-ai/claude-code/cli.js:1919:29690)\n    at async file:///usr/lib/node_modules/@anthropic-ai/claude-code/cli.js:1919:24439\n    at async aq0 (file:///usr/lib/node_modules/@anthropic-ai/claude-code/cli.js:1919:4362)\n    at async u01 (file:///usr/lib/node_modules/@anthropic-ai/claude-code/cli.js:1919:24409)","timestamp":"2025-09-23T22:38:33.445Z"}]