Add support for `history -c` to clear terminal command history

[Copilot]

• [x] Explore repository structure and understand terminal implementation
• [x] Add custom history command handler in Swift (TerminalInstance.swift)
• [x] Connect Swift handler to JavaScript function to clear history
• [x] Address code review feedback (improve command parsing)
• [x] Add detailed comments and maintain consistency with existing code
• [x] Final code review - no issues found
• [x] Security scan - no vulnerabilities
• [x] Address PR review: Use fallthrough for cleaner code
• [x] Complete task

Summary

Successfully implemented support for history -c command to clear terminal command history. The implementation has been refined based on code review to use fallthrough for better code organization.

Implementation

• Added custom handler in TerminalInstance.swift for history commands
• history -c clears JavaScript-based history in local-echo.js
• Other history commands use fallthrough to delegate to default case
• Includes comprehensive comments and validation

Original prompt

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This section details on the original issue you should resolve

<issue_title>Cannot clear history of commands used in terminal</issue_title> <issue_description>In general (shell-based) terminal, running history -c can clear all the history of commands used. However, this sentence did not work in terminal of this APP and I did not find any other relevant setups except item Close Workspace, which seem to be unpractical for ongoing projects.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes thebaselab/codeapp#1266

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[bummoblizard]

@copilot evaluate my comment and make any necessary changes

[Copilot]

@copilot evaluate my comment and make any necessary changes

Updated to use fallthrough as requested in commit 8ff488f.