Add support for brev open code/cursor commands and default editor setting

[devin-ai-integration]

Add support for brev open code/cursor commands and default editor setting

Summary

This PR implements multi-editor support for the brev open command, allowing users to explicitly choose between VSCode and Cursor, and set a default editor preference.

Key Changes:

• New command syntax: brev open <workspace> code and brev open <workspace> cursor
• Default editor setting: brev open --set-default <editor> to configure preference
• Backward compatibility: Existing brev open <workspace> continues to work
• Personal settings: New infrastructure to store user preferences in ~/.brev/personal_settings.json
• Cursor utilities: Full cursor support with path detection, extension management, and SSH integration

Breaking Change: Removed the existing --cursor flag (which was non-functional) in favor of the new argument-based approach.

Review & Testing Checklist for Human

⚠️ High Priority (5 items)

• Verify compilation and basic functionality - Ensure the code compiles and existing brev open <workspace> usage still works
• Test new command syntax - Verify brev open <workspace> code and brev open <workspace> cursor work correctly
• Validate Cursor integration - Test that Cursor actually opens correctly and extensions install (I made assumptions about CLI compatibility with VSCode)
• Check default editor setting - Test brev open --set-default cursor persists preference and brev open <workspace> uses it
• Verify error handling - Test with missing executables, invalid editor types, and permission issues with settings file

Recommended Test Plan:

1. Compile and run existing workflows to ensure no regressions
2. Test each new command variant with both editors installed and missing
3. Verify settings persistence across CLI sessions
4. Test edge cases like invalid arguments, corrupted settings file, etc.

---

Diagram

%%{ init : { "theme" : "default" }}%%
graph TB
    subgraph Legend
        L1["Major Edit"]:::major-edit
        L2["Minor Edit"]:::minor-edit  
        L3["Context/No Edit"]:::context
    end
    
    OpenCmd["pkg/cmd/open/open.go<br/>Main command logic"]:::major-edit
    UtilPkg["pkg/util/util.go<br/>Editor utilities"]:::major-edit
    FilesPkg["pkg/files/files.go<br/>Settings management"]:::major-edit
    
    PersonalSettings["PersonalSettings struct<br/>Default editor storage"]:::minor-edit
    CursorUtils["Cursor utilities<br/>TryRunCursorCommand, etc."]:::minor-edit
    
    OpenCmd -->|"uses"| UtilPkg
    OpenCmd -->|"reads/writes"| FilesPkg  
    FilesPkg -->|"contains"| PersonalSettings
    UtilPkg -->|"contains"| CursorUtils
    
    classDef major-edit fill:#90EE90
    classDef minor-edit fill:#87CEEB  
    classDef context fill:#FFFFFF

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Notes

• Untested locally: Could not test due to missing Go environment - compilation verification needed
• Cursor assumptions: Implementation assumes Cursor uses VSCode-compatible CLI arguments and extension system
• Session info: Implemented by Devin AI for @theFong
• Session URL: https://app.devin.ai/sessions/d767e8c9fa3e4eacacdbba260309eb75

[devin-ai-integration]

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[theFong]

When I run the set default flow, I get the following error resulting in me not being able to set default

➜  brev-cli git:(devin/1752610763-add-editor-support) ./brev open --set-default cursor
accepts between 1 and 2 arg(s), received 0

[theFong]

Setting the default ide results in a strange success error message

➜  brev-cli git:(devin/1752610763-add-editor-support) ./brev open --set-default cursor
Default editor set to %!!(string=cursor)s(MISSING)