PR review: batch inline comments into a submittable review so the agent acts once, not per-comment

PR review: batch inline comments into a submittable review so the agent acts once, not per-comment

### Describe the feature or problem you'd like to solve

When reviewing a pull request in the desktop app's diff viewer, each inline review comment I post is dispatched to the agent **immediately and individually** — every comment triggers its own agent turn that acts right away.

This means if I'm still working through a review — leaving five comments across several files — the agent starts editing after comment #1, while I'm still writing comments #2–#5. My changes and its changes interleave, the PR "moves around" under me, and I can't compose a complete review before the agent responds.

On **GitHub web**, review comments work differently: they're collected into a **pending review** and only released together when I click **Submit review**. The reviewer finishes the entire pass first; consumers act once, on submit.

### Proposed solution

Add a **pending-review / batch-submit mode** to the diff-review experience, matching GitHub web:

- Inline comments I add accumulate as a **pending (draft) review** and are **not** sent to the agent as I type them.
- A **Submit review** action releases the whole batch at once.
- The agent then acts on the complete set in one pass, rather than reacting comment-by-comment.

Ideally this is the default (or a toggle), so the per-comment behavior becomes opt-in for people who want immediate action.

### Example prompts or workflows

- I review a 6-file PR and leave 8 comments. Today the agent starts fixing after the first comment; my later comments land while it's mid-edit. With batch submit, I finish all 8, click Submit, and the agent addresses them together — no interleaving.

### Additional context

Current workaround is to tell the agent "wait until I'm done reviewing before acting," but that's a per-session nudge, not an enforced gate — the agent can still act on a comment before I finish. A real pending-review/submit boundary solves it at the product layer. The per-comment dispatch appears specific to the desktop diff viewer; the GitHub web batched-submit model is the desired parity.

---
| Field | Value |
| --- | --- |
| App version | 1.0.21 |
| OS | Windows 10.0.26200 |
| Theme | GitHub |
| Path | /chat |
| Tenure | Week 4 |

Bắt đầu từ trình xem diff của ứng dụng desktop và hành vi dispatch inline-comment hiện tại được mô tả ở đây. Theo dõi cách các comment được gửi đến agent, sau đó xác định trạng thái review đang chờ và ranh giới Submit review. Hoàn tất có nghĩa là nhiều comment vẫn không hoạt động cho đến một lần submit và được xử lý cùng nhau.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.