fix: check byte length on name validation instead of character count

[AlexAndBear]

Description

Related Issue

• Fixes Renaming file-function in web is restricted to 63 characters opencloud#1404
• Relates Restrict the length of the resource name #772

How Has This Been Tested?

• test environment:
• test case 1:
• test case 2:
• ...

Types of changes

• Bugfix
• Enhancement (a change that doesn't break existing code or deployments)
• Breaking change (a modification that affects current functionality)
• Technical debt (addressing code that needs refactoring or improvements)
• Tests (adding or improving tests)
• Documentation (updates or additions to documentation)
• Maintenance (like dependency updates or tooling adjustments)

[Copilot]

Pull Request Overview

This PR changes resource name validation from checking character count to checking byte length, addressing issues with multi-byte Unicode characters that could cause validation to pass but fail at the backend level.

• Updates validation logic to use TextEncoder for accurate byte length calculation
• Increases the maximum allowed bytes from 63 characters to 256 bytes
• Simplifies error messages to be more generic

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
packages/web-pkg/src/constants.ts	Adds new RESOURCE_NAME_MAX_BYTES constant (256)
packages/web-pkg/src/composables/actions/helpers/useIsResourceNameValid.ts	Replaces character length validation with byte length validation using TextEncoder
packages/web-pkg/tests/unit/composables/actions/helpers/useIsResourceNameValid.spec.ts	Updates test cases to use new byte-based validation and simplified error messages

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[kulmann]

Super nice improvement 🥇