enhance code block language picker

[AlexAndBear]

Description

Before

After

This change replaces the oc-select in the code block node view with a native <select> to achieve a cleaner, code-editor-like language picker without heavy style overrides.

It also updates the local styling and keeps explicit disabled-state visuals (color + cursor), and adapts unit tests to the native select behavior.

Related Issue

• Fixes N/A

How Has This Been Tested?

• test environment: local development environment (macOS)
• test case 1: pnpm test:unit --run packages/web-pkg/tests/unit/editor/components/CodeBlockComponent.spec.ts
• test case 2: verified readonly/disabled visual state and cursor behavior in the code block language select

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)

[AlexAndBear]

This PR is debatable, but the native select with minor styling looks much cleaner and better aligned with the current UI. Using oc-select here would require a lot of CSS overrides, which adds unnecessary complexity and increases the risk of styling issues