Use spec.creationTime consistently for reply timestamps (#207)

Replies used `metadata.creationTimestamp` while comments used `spec.creationTime`. Since `metadata.creationTimestamp` doesn't necessarily represent the actual creation time, both should use `spec.creationTime`.

**Changes:**
- Updated `reply-item.ts` line 122 to use `reply?.spec.creationTime` instead of `reply?.metadata.creationTimestamp`

```typescript
// Before
.creationTime="${this.reply?.metadata.creationTimestamp ?? undefined}"

// After  
.creationTime="${this.reply?.spec.creationTime}"
```

This aligns replies with comments, which already use `spec.creationTime`.

> [!WARNING]
>
> <details>
> <summary>Firewall rules blocked me from connecting to one or more addresses (expand for details)</summary>
>
> #### I tried to connect to the following addresses, but was blocked by firewall rules:
>
> - `pkg.pr.new`
>   - Triggering command: `/usr/local/bin/node node /usr/local/bin/pnpm install` (dns block)
>
> If you need me to access, download, or install something from one of these locations, you can either:
>
> - Configure [Actions setup steps](https://gh.io/copilot/actions-setup-steps) to set up my environment, which run before the firewall is enabled
> - Add the appropriate URLs or hosts to the custom allowlist in this repository's [Copilot coding agent settings](https://github.com/halo-dev/plugin-comment-widget/settings/copilot/coding_agent) (admins only)
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<details>

<summary>Original prompt</summary>

> 
> ----
> 
> *This section details on the original issue you should resolve*
> 
> <issue_title>回复的时间不正确</issue_title>
> <issue_description>目前项目中回复采用的时间是 `metadata. creationTimestamp`
> 
> https://github.com/halo-dev/plugin-comment-widget/blob/bf6435b978dd33da9ccbff220ea1f9907e4cf41b/packages/comment-widget/src/reply-item.ts#L122
> 
> 但评论采用的时间又是 `spec. creationTime`
> 
> https://github.com/halo-dev/plugin-comment-widget/blob/bf6435b978dd33da9ccbff220ea1f9907e4cf41b/packages/comment-widget/src/comment-item.ts#L120
> 
> 应当使其保持一致，建议统一使用 `spec. creationTime`， `metadata. creationTimestamp` 并不一定代表真实的创建时间。</issue_description>
> 
> ## Comments on the Issue (you are @copilot in this section)
> 
> <comments>
> </comments>
> 


</details>



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- Fixes #206

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Author: Copilot

packages/comment-widget/src/reply-item.ts

@@ -119,7 +119,7 @@ export class ReplyItem extends LitElement {
         .userAvatar="${handleReplyAvatar(this.reply)}"
         .userDisplayName="${this.reply?.owner.displayName}"
         .content="${this.reply?.spec.content || ''}"
-        .creationTime="${this.reply?.metadata.creationTimestamp ?? undefined}"
+        .creationTime="${this.reply?.spec.creationTime}"
         .approved=${this.reply?.spec.approved}
         .breath=${this.isQuoteReplyHovered}
         .userWebsite=${this.reply?.spec.owner.annotations?.website}