Implement brev copy command for file transfer

[devin-ai-integration]

Implement brev copy command for file transfer

Summary

This PR implements a new brev copy command that enables copying files between local machine and remote workspaces using scp, following the same patterns as the existing brev shell command.

Key features:

• Bidirectional copying: brev copy workspace:/remote/path /local/path and brev copy /local/path workspace:/remote/path
• Automatic workspace startup if stopped (same as shell command)
• SSH connection handling with proper waiting and refresh logic
• --host flag to copy to/from host machine instead of container
• Aliases: cp, scp
• Appears in SSH Commands section alongside shell, open, etc.

Implementation approach:

• Created new pkg/cmd/copy/copy.go following shell.go patterns
• Reuses workspace resolution, SSH setup, and polling utilities
• Uses strings.Split for workspace:path parsing (similar to portforward command)
• Refactored into smaller functions to pass linting (function length limits)

Review & Testing Checklist for Human

Critical items requiring manual verification:

• End-to-end file transfer testing: Test actual copying in both directions with real workspaces - this is the core functionality that couldn't be tested locally
• Workspace startup logic: Verify stopped workspaces start correctly before copying (test with brev stop then brev copy)
• Error handling verification: Test invalid workspace names, non-existent paths, SSH failures, permission errors
• Argument parsing edge cases: Test paths containing colons, special characters, spaces (e.g. workspace:/path:with:colons, paths with spaces)
• Host flag functionality: Verify --host flag correctly targets host vs container

Recommended test plan:

1. Create test files locally and in a workspace
2. Test upload: brev copy /local/test.txt myworkspace:/tmp/test.txt
3. Test download: brev copy myworkspace:/tmp/test.txt /local/downloaded.txt
4. Test with stopped workspace to verify auto-start
5. Test --host flag behavior
6. Test error scenarios (invalid paths, non-existent workspace)

---

Diagram

%%{ init : { "theme" : "default" }}%%
graph TD
    main.go --> cmd.go["pkg/cmd/cmd.go<br/>(Minor Edit)"]
    cmd.go --> copy.go["pkg/cmd/copy/copy.go<br/>(Major Edit - New File)"]
    
    copy.go --> util.go["pkg/cmd/util/util.go<br/>(Context)"]
    copy.go --> shell.go["pkg/cmd/shell/shell.go<br/>(Context)"]
    copy.go --> refresh.go["pkg/cmd/refresh/refresh.go<br/>(Context)"]
    
    copy.go -.->|"reuses patterns"| shell.go
    copy.go -.->|"workspace resolution"| util.go
    copy.go -.->|"SSH refresh logic"| refresh.go
    
    cmd.go -->|"registers command"| copy.go
    
    subgraph Legend
        L1["Major Edit"]:::major-edit
        L2["Minor Edit"]:::minor-edit  
        L3["Context/No Edit"]:::context
    end
    
    classDef major-edit fill:#90EE90
    classDef minor-edit fill:#87CEEB
    classDef context fill:#FFFFFF

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Notes

• Security consideration: Uses exec.Command with user input but sshAlias is validated through workspace resolution
• Pattern consistency: Closely follows shell.go patterns for workspace handling, SSH setup, and error handling
• Linting compliance: Refactored into smaller functions to meet function length requirements
• Future enhancement: User mentioned considering rsync for v2 - current scp implementation provides foundation

Link to Devin run: https://app.devin.ai/sessions/e7fbaf33368343fc9d32002721a55ea0
Requested by: Alec Fong (@theFong)

[devin-ai-integration]

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[theFong]

the success message looks like the following

⣽ waiting for instance to be ready... ✓ Successfully copied %!!(string=go.mod)s(MISSING) → %!!(string=test-deploy:~)s(MISSING) (%!!(time.Duration=1695000000)v(MISSING))

we need to put it on a new line and use the proper func to print.

[theFong]

what I meant by the new line is that I want to format like

⣻ waiting for SSH connection to be available 
✓ Successfully copied go.mod → test-deploy:~ (1.668s)

[theFong]

Output: Warning: Permanently added 'ec2-54-91-119-233.compute-1.amazonaws.com' (ED25519) to the list of known hosts.
scp: local "my-dir" is not a regular file
scp: failed to upload file my-dir to ~

can we support directories automatically?