apply_patch stores deleted binary in session history, permanently exceeding CAPI 5 MB limit

### Describe the bug

When `apply_patch` deletes a large binary file, its `tool.execution_complete` event stores the entire deleted binary as a textual diff in `result.detailedContent`.

This result remains in conversation history. Subsequent requests exceed CAPI Responses' 5 MB limit, and `/compact` fails for the same reason, leaving the session unrecoverable through the CLI.

### Affected configuration

- GitHub Copilot CLI 1.0.71-0
- Linux
- Model: GPT-5.6 Sol (`gpt-5.6-sol`)
- Context window: 1.1M
- Reasoning effort: high
- Interactive session later resumed with `copilot --resume=`

The model, context-window size, and reasoning effort may affect when compaction runs, but the persisted binary tool output appears to be the direct cause of the 5 MB transport failure.

### Observed sequence

1. Copilot used `apply_patch` to delete a large ELF executable.
2. The persisted event contained:
- `result.detailedContent`: 22,810,594 characters
- Serialized JSONL record: 72,155,553 bytes
- Tool telemetry: 111,879 removed lines
3. `events.jsonl` grew to 118,622,622 bytes.
4. Further requests failed with:

> The request is too large to send through CAPI Responses. Try shortening the conversation or prompt. (5.0 MB request; 5.0 MB limit)

5. Automatic/manual compaction failed with the same error.

### Expected behavior

Binary content should not be persisted as a textual patch. The CLI should retain deletion metadata while omitting or capping oversized `detailedContent`.

After a request-size failure, oversized tool output should be evicted so compaction can recover the session.

### Workaround and root-cause confirmation

After backing up the session, I replaced the oversized `detailedContent` with a short marker. This reduced the event log from 118.6 MB to 46.5 MB and eliminated the CAPI request-size failure.

### Related issues

This resembles #3767, but that issue covered inline attachments and was fixed in v1.0.62. This report concerns persisted `apply_patch` output in v1.0.71.

The session also developed malformed JSONL records that prevented resume, reported separately in #4098. The shared root cause is not proven, although the unusually large write may have widened the failure window.

I have not attached `events.jsonl` because it contains conversation and tool history.

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Investigated and filed with assistance from GitHub Copilot CLI.

在写入 events.jsonl 并包含到 CAPI Responses 请求之前，跟踪 apply_patch 的输出经过 tool.execution_complete 事件的过程，尤其是 result.detailedContent。使用一个已删除的大型二进制文件进行复现，并执行 /compact。当删除元数据得到保留、不会持久化过大的文本内容，并且压缩能在请求大小失败后恢复时，即表示完成。

由索引模型根据 Issue 内容生成。