### Description
This pull request introduces the core functionality for creating and updating posts, completing the backend CRUD operations for the `post` feature. It includes new API endpoints, database schema changes, and corresponding updates across the entire application stack from the database layer to the frontend.
#### Backend API
- **Added new authenticated endpoints:**
- `POST /post`: To create a new post.
- `PUT /post/{id}`: To update an existing post.
- Implemented the full vertical slice for these operations, including:
- `CreatePostUseCase` and `UpdatePostUseCase`.
- Repository and DB service methods for creating, updating, and associating posts with labels.
- Transactional database operations to ensure data integrity when creating/updating posts and their associated labels.
#### Database
- Added a new migration to include an `"order"` column in the `post_label` table.
- This column preserves the user-defined order of labels for each post.
- Queries have been updated to fetch and sort labels based on this new column.
#### API Schema & Documentation
- Enhanced `utoipa` OpenAPI documentation with more specific formats for data types:
- `#[schema(format = Uri)]` for URLs like `preview_image_url`.
- `#[schema(format = Email)]` for user emails.
- `#[schema(format = DateTime)]` for timestamps.
- Standardized the `published_time` field to use the RFC3339 string format instead of a numeric timestamp, improving API clarity and interoperability.
#### Frontend
- Updated the `PostInfoResponseDto` in the frontend to correctly parse the new `DateTime` (ISO string) format for `published_time`.
#### Refactoring
- Renamed `get_full_post` to a more descriptive `get_post_by_id` across the post feature module for better code clarity.
### Package Changes
```toml
utoipa = { version = "5.4.0", features = [
"actix_extras",
"non_strict_integers",
"url",
] }
```
### Screenshots
_No response_
### Reference
Resolves#104
### Checklist
- [x] A milestone is set
- [x] The related issuse has been linked to this branch
Reviewed-on: #108
Co-authored-by: SquidSpirit <squid@squidspirit.com>
Co-committed-by: SquidSpirit <squid@squidspirit.com>
### Description
This PR integrates the **`utoipa`** and **`utoipa-redoc`** crates to automatically generate OpenAPI-compliant API documentation for the backend project.
#### Overview
To improve development efficiency and API maintainability, this change introduces `utoipa` to automate the API documentation process. By adding specific attribute macros to the source code, we can generate detailed API specifications directly and serve them through an interactive UI provided by `utoipa-redoc`.
#### Key Changes
* **Dependencies Added**
* Added `utoipa`, `utoipa-gen`, and `utoipa-redoc` to `Cargo.toml`.
* `utoipa` is used to define OpenAPI objects.
* `utoipa-redoc` is used to serve the ReDoc documentation UI.
* **Code Refactoring**
* **HTTP handler logic** in each feature (`auth`, `image`, `post`) has been extracted from the `..._web_routes.rs` files into their own dedicated files (e.g., `get_post_by_id_handler.rs`). This makes the code structure cleaner and simplifies adding documentation attributes to each handler.
* Renamed the `PostController` method from `get_full_post` to `get_post_by_id` for a more RESTful-compliant naming convention.
* **API Doc Annotation**
* Added `#[derive(ToSchema)]` or `#[derive(IntoParams)]` to all DTOs (Data Transfer Objects) so they can be recognized by `utoipa` to generate the corresponding schemas.
* Added the `#[utoipa::path]` macro to all HTTP handler functions, describing the API's path, HTTP method, tags, summary, expected responses, and security settings.
* **Doc Aggregation & Serving**
* Added an `..._api_doc.rs` file in each feature module to aggregate all API paths within that module.
* Added a new `api_doc.rs` file in the `server` crate to merge the OpenAPI documents from all features, set global information (like title, version, and the OAuth2 security scheme), and serve the documentation page on the `/redoc` route using `Redoc::with_url`.
### Package Changes
```toml
utoipa = { version = "5.4.0", features = ["actix_extras"] }
utoipa-redoc = { version = "6.0.0", features = ["actix-web"] }
```
### Screenshots

### Reference
Resolves#103
### Checklist
- [x] A milestone is set
- [x] The related issuse has been linked to this branch
Reviewed-on: #106
Co-authored-by: SquidSpirit <squid@squidspirit.com>
Co-committed-by: SquidSpirit <squid@squidspirit.com>
### Description
- `.sqlx` should be check into version control system because it is required when rust compiling if there is no available online sql server.
### Package Changes
_No response_
### Screenshots
_No response_
### Reference
__NO_ISSUE__
### Checklist
- [x] A milestone is set
- [ ] The related issuse has been linked to this branch
Reviewed-on: #99
Co-authored-by: SquidSpirit <squid@squidspirit.com>
Co-committed-by: SquidSpirit <squid@squidspirit.com>