feat(DropUpload): add DropUpload component

[ArgoZhang]

add DropUpload component

Summary of the changes (Less than 80 chars)

简单描述你更改了什么, 不超过80个字符；如果有关联 Issue 请在下方填写相关编号

Description

fixes #5224

Regression?

• Yes
• No

[If yes, specify the version the behavior has regressed from]

[是否影响老版本]

Risk

• High
• Medium
• Low

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Verification

• Manual (required)
• Automated

Packaging changes reviewed?

• Yes
• No
• N/A

☑️ Self Check before Merge

⚠️ Please check all items below before review. ⚠️

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• Merge the latest code from the main branch

Summary by Sourcery

New Features:

• Introduce a new DropUpload component that allows users to upload files by dragging and dropping them or by clicking to select files.

[sourcery-ai]

Reviewer's Guide by Sourcery

This pull request introduces a new DropUpload component, enhancing the file upload functionality. It includes styling updates, javascript changes, and a new razor component.

No diagrams generated as the changes look simple and do not need a visual representation.

File-Level Changes

Change	Details	Files
Added DropUpload component with associated styling and functionality.	Created DropUpload.razor.cs with properties for customizing the component. Created DropUpload.razor with the basic layout and structure. Added new CSS variables and styles for the drop area in UploadBase.razor.scss. Modified upload.js to include click event for the new drop area. Added new scss variables for the drop area in bootstrapblazor.scss.	src/BootstrapBlazor/Components/Upload/DropUpload.razor.cs src/BootstrapBlazor/Components/Upload/DropUpload.razor src/BootstrapBlazor/Components/Upload/UploadBase.razor.scss src/BootstrapBlazor/wwwroot/modules/upload.js src/BootstrapBlazor/wwwroot/scss/theme/bootstrapblazor.scss
Updated the sample page to include the new DropUpload component.	Added a new DemoBlock for the DropUpload component in Uploads.razor.	src/BootstrapBlazor.Server/Components/Samples/Uploads.razor
Minor changes to other upload components and a sample page.	Added a try-catch block to the SynthesizerService in Synthesizers.razor.cs. Added comments to the AvatarUpload.razor.cs, ButtonUpload.razor.cs, InputUpload.razor.cs, and SingleUploadBase.cs files.	src/BootstrapBlazor.Server/Components/Samples/Speeches/Synthesizers.razor.cs src/BootstrapBlazor/Components/Upload/AvatarUpload.razor.cs src/BootstrapBlazor/Components/Upload/ButtonUpload.razor.cs src/BootstrapBlazor/Components/Upload/InputUpload.razor.cs src/BootstrapBlazor/Components/Upload/SingleUploadBase.cs

Assessment against linked issues

Issue	Objective	Addressed	Explanation
#5224	Add a new DropUpload component to the library	✅
#5224	Implement drag and drop file upload functionality	✅
#5224	Provide a user-friendly interface for file uploads	✅

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[sourcery-ai]

Hey @ArgoZhang - I've reviewed your changes - here's some feedback:

Overall Comments:

• The empty catch block in Synthesizers.razor.cs silently swallows exceptions. This could hide important errors from users and make debugging difficult. Consider at least logging the exception or showing an error message to users.
• DropUpload.razor.cs contains a hardcoded footer string ('just a test footer string') that appears to be test/development code. This should be removed or replaced with a proper default value.

Here's what I looked at during the review

• 🟢 General issues: all looks good
• 🟢 Security: all looks good
• 🟢 Testing: all looks good
• 🟢 Complexity: all looks good
• 🟢 Documentation: all looks good

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (b6f47f0) to head (d247c66).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #5236   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          635       637    +2     
  Lines        28248     28317   +69     
  Branches      4066      4078   +12     
=========================================
+ Hits         28248     28317   +69     

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