fix(proxy): handle CRLF SSE delimiters (#1787)

[zerone0x]

Summary / 概述

• handle SSE blocks delimited by \r\n\r\n by normalizing CRLF and splitting with a shared helper
• apply the helper across all SSE parsing paths

Related Issue / 关联 Issue

Fixes #1787

Screenshots / 截图

Before / 修改前	After / 修改后

Checklist / 检查清单

• pnpm typecheck passes / 通过 TypeScript 类型检查
• pnpm format:check passes / 通过代码格式检查
• cargo clippy passes (if Rust code changed) / 通过 Clippy 检查（如修改了 Rust 代码）
• Updated i18n files if user-facing text changed / 如修改了用户可见文本，已更新国际化文件

[farion1231]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Chef's kiss.

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