File dropzone - Add custom error messages for validation

[prashanthr6383]

📄 Summary of Changes

• Added custom error message for

invalid type, invalid size. invalid name, invalid count

💭 Type of Change

• Bug fix (fixes an issue)
• New feature (adds functionality)
• Configuration change (modifies scaling or properties of existing infrastructure & services)
• Documentation change
• Other

📋 Test Plan

✅ Self Code Review Checklist

PR authors and reviewers, please verify that all of these items have been completed.

• My code is clean and readable
• I followed standard conventions
• Component code is WCAG 2.2 compliant (if applicable)
• I have made theme files changes (if applicable)
• I have made documentation changes (if applicable)
• I have made Storybook changes including usage documentation (if applicable)
• I have tested the component thoroughly in Storybook including RTL rendering (if applicable)

🔗 Work Item

Issue #1064

[github-actions]

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[Copilot]

Pull request overview

Adds support for custom, per-validation error messaging in modus-wc-file-dropzone, allowing consumers to override default validation messages for invalid type, name, size, and count.

Changes:

• Introduces a new errorMessages prop (typed as IFileDropzoneErrorMessages) and wires it into the internal getErrorMessage() fallback logic.
• Updates Storybook examples to demonstrate setting errorMessages (including a docs snippet showing property assignment).
• Adds Jest tests to verify custom message selection and fallback behavior (including legacy invalidFileTypeMessage fallback).

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/components/modus-wc-file-dropzone/modus-wc-file-dropzone.tsx	Adds IFileDropzoneErrorMessages + errorMessages prop and uses it in validation messaging fallbacks.
src/components/modus-wc-file-dropzone/modus-wc-file-dropzone.stories.ts	Documents and demonstrates errorMessages usage in Storybook (controls + example).
src/components/modus-wc-file-dropzone/modus-wc-file-dropzone.spec.ts	Adds tests covering custom error message selection and fallback behavior.
src/components/modus-wc-file-dropzone/readme.md	Updates auto-generated docs to include the new errorMessages prop.
src/custom-elements.json	Updates custom elements manifest to include error-messages.
src/components.d.ts	Updates generated typings to export and surface IFileDropzoneErrorMessages on the component.

[ElishaSamPeterPrabhu]

The current implementation provides the ability to customize existing error state messages, but it does not support customizing the error state behavior itself.

Because of this limitation, it does not address the issue mentioned. They are trying to display an error state when uploads across multiple instances collectively exceed the maximum allowed count. However, with the current implementation, the count resets on each upload action, so this error state is not triggered.

@Sunder005 is this the expectation?