Telemetry and Cache Explorer completely broken specifically for kimi-k2.7-code model

### Short summary

_No response_

### Affected version or release

Github Copilot CLI v1.0.70

### Installation context

_No response_

### What happened?

Hey team,

Found a breaking telemetry bug in agent-host-copilotcli that only happens when using the kimi-k2.7-code model. Other models seem to track just fine.

Basically, the token tracking is completely dead, which then cascades and breaks the Cache Explorer dashboard.

1. Zero Token Telemetry Bug
As shown in the first screenshot, the agent successfully runs through 17 turns and 24 tool calls with 0 errors. However, all token metrics (Total Input, Total Output, Total Cached, Total Tokens) are completely stuck at 0. The execution works fine, but the telemetry data is missing.

2. Broken Cache Explorer (Cascading Error)
Because the token counts are missing, the Cache Explorer is completely blind. It shows 0.00% cache hit and throws a fake "Likely cache expiration (~5 min)" warning.

But if you look closely at the timestamps, the gap between Turn 15 and Turn 16 is only 13 seconds (Turn 15 ended at 07:09:51 and Turn 16 started at 07:10:04). There is no way the prompt cache expired in 13 seconds. Both input tok and cached tok fields are completely blank.

It looks like the CLI is either failing to parse the token usage block from Kimi's API response, or it's completely forgetting to pass the caching headers for this specific model.

### Steps to reproduce

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### Expected behavior

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### Additional context

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首先，在 Github Copilot CLI v1.0.70 中使用 kimi-k2.7-code 模型复现零 token 遥测，然后跟踪 token 使用量解析以及传递给 Cache Explorer 的数据。完成的标准是输入、输出、缓存和总 token 指标均能正确填充，并且仪表板不再报告错误的缓存过期警告。

由索引模型根据 Issue 内容生成。