### Description
This PR updates the application to handle posts that may not have a publication date (e.g., drafts) by making the `published_time` field optional across the entire post feature stack.
This ensures that draft posts can be processed and rendered without causing errors, and prevents search engine metadata from being generated for content that is not yet published.
#### Key Changes:
* **DTO & Schema (`postInfoResponseDto.ts`):**
* The Zod schema for `PostInfoResponseSchema` has been updated to mark `published_time` as `.nullable()`.
* The `PostInfoResponseDto` class now correctly handles a `null` value from the API, mapping it to `Date | null`.
* **Domain Entity (`postInfo.ts`):**
* The core `PostInfo` entity's `publishedTime` property is now typed as `Date | null` to reflect the business logic that a post may be unpublished.
* **View Model (`postInfoViewModel.ts`):**
* Updated `publishedTime` to be `Date | null`.
* Added a new `isPublished` boolean getter for convenient conditional logic in the UI.
* The `formattedPublishedTime` getter now returns `string | null`.
* Dehydration and rehydration logic (`dehydrate`/`rehydrate`) has been updated to correctly handle the nullable `publishedTime`.
* **UI Component (`PostContentPage.svelte`):**
* The component now uses the new `isPublished` flag to conditionally render the `<StructuredData>` component for SEO. This ensures that structured data is only included for posts that have been officially published.
### Package Changes
_No response_
### Screenshots
_No response_
### Reference
Resolves#118
### Checklist
- [x] A milestone is set
- [x] The related issuse has been linked to this branch
Reviewed-on: #121
Co-authored-by: SquidSpirit <squid@squidspirit.com>
Co-committed-by: SquidSpirit <squid@squidspirit.com>
### Description
- Change the format of color response
```json
{
"red": 0,
"green": 255,
"blue": 128,
"alpha": 255
}
```
- The relationship between the label's background color and its highlight color is calculated. The method involves first converting the RGB color value to HSL, then decreasing the L (lightness) component, and finally converting it back to RGB.
### Package Changes
```json
{
"zod": "^4.0.5"
}
```
### Screenshots
|Desktop|Mobile|
|-|-|
|||
### Reference
Resolves#44
### Checklist
- [x] A milestone is set
- [x] The related issuse has been linked to this branch
Reviewed-on: #64
Co-authored-by: SquidSpirit <squid@squidspirit.com>
Co-committed-by: SquidSpirit <squid@squidspirit.com>
