完善 Checkpoint 变更对比、差异展示与 Web 端交互修复

[Yumiue]

变更概述

• Checkpoint 链路：完善变更对比与差异展示，补齐 per-edit 快照增强和恢复能力
• Web 端修复：修正模型切换链路一致性，优化 ChatInput 多模态交互，修复 FileChangePanel 文件变更面板展示
• Patch 解析增强：改进 unified diff 解析器，支持更准确的文件变更内容渲染
• Bypass 机制：Gateway 层新增 bypass 通路，优化 Runtime 桥接层
• 发布构建：补齐 goreleaser 配置，Web 端发布版本自动构建依赖

主要变化

Checkpoint

• 增强 PerEditSnapshotStore 快照捕获与比较能力
• 新增 checkpoint_restore.go 恢复逻辑
• 补齐 end-of-turn checkpoint 创建与查找测试

Web 前端

• ModelSelector：修复模型切换状态不一致问题
• ChatInput：支持多模态输入，修复快捷键冲突
• FileChangePanel：重构变更文件展示，适配 enhanced diff 格式
• PatchParser：增强 unified diff 解析，支持 rename/copy/new file 模式
• EventBridge：完善前后端事件桥接

Gateway / Runtime

• Gateway Bootstrap 新增 bypass 模式
• Runtime 桥接层接口优化

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[fennoai]

Found 2 noteworthy issues after code quality, performance, security, and documentation passes.

[fennoai]

setSelected(m) has already committed the optimistic UI state by the time this RPC runs, but the failure path only logs to the console. If setSessionModel / selectProviderModel fails, the dropdown keeps showing the new model even though the backend state never changed, and the deferred path has the same problem. Please either revert the optimistic state on error or surface a toast and re-sync from listModels() after a failed apply.

[fennoai]

This new filter drops every run-scoped file entry unless parseUnifiedPatch() produced at least one rendered diff line. That means legitimate backend-reported changes with no hunk body, such as zero-byte file add/delete or rename/copy-only patches, disappear from FileChangePanel even though diff.files still reports them. The UI should preserve those entries and treat the parsed patch as optional metadata instead of a hard requirement.

[codecov]

Codecov Report

❌ Patch coverage is 69.40299% with 123 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
internal/checkpoint/per_edit_snapshot.go	67.33%	36 Missing and 29 partials ⚠️
internal/runtime/checkpoint_restore.go	57.89%	14 Missing and 10 partials ⚠️
internal/cli/gateway_runtime_bridge.go	80.58%	14 Missing and 6 partials ⚠️
internal/cli/web_command.go	52.63%	8 Missing and 1 partial ⚠️
internal/gateway/bootstrap.go	63.63%	4 Missing ⚠️
internal/runtime/compact.go	0.00%	0 Missing and 1 partial ⚠️

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