Remove legacy "package" temporary install in favour of just selecting out necessary files from source directly

[dsyme]

@pelikhan Just to mention we have this legacy thing where running an install of a single workflow like

gh aw add https://github.com/githubnext/gh-aw/blob/v0.37.7/.github/workflows/copilot-agent-analysis.md

does this temporary "install" of the whole "package" of workflows from that repository, then selects out just the one workflow file to install. The package gets "installed" to the tmp/ directory then deleted.

Package githubnext/gh-aw already exists. Updating...

It's legacy from when we did packaging via collected packages of workflows rather than single files.

I haven't removed it as yet as it may require a bit of work to carefully dig things out and check things w.r.t. how multi-file workflows are handled on install.

[dsyme]

I'm going to park this for now. What we have works right now, and it is indeed very subtle to remove this without messing with how our imports work. The code paths are just hack laid over legacy laid over hack while actually doing something sensible E2E.

I will do this carefully later

[github-actions]

Assigning to @mnkiefer based on recent CLI contributions. This refactoring task involves removing the legacy package installation flow and simplifying to direct file selection.

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[github-actions]

Assigned to @dsyme based on your expertise with CLI features and refactoring work. This legacy package install cleanup aligns with recent CLI improvements.

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[github-actions]

Assigning to @dsyme based on your recent contributions to the CLI and expertise in this area, as shown by opening this issue. This refactoring task aligns well with your work on the CLI codebase.

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[github-actions]

👋 @dsyme - Assigning this to you since you opened it and have been actively working on CLI improvements recently. This legacy package install cleanup would be a great refactoring task.

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[github-actions]

Assigning to @pelikhan based on your extensive work on the CLI refactoring and codebase architecture. This legacy package installation cleanup aligns with recent repository modernization efforts.

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