Re-prompt user for project name instead of exiting, spinner for package install

[tcdent]

Requested by @areibman

[tcdent]

@srilaasya Is this the expected behavior with llms.txt? I am not sure when it's generating.

[codecov]

Codecov Report

Attention: Patch coverage is 54.45545% with 46 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
agentstack/cli/init.py	4.54%	21 Missing ⚠️
agentstack/cli/spinner.py	75.00%	13 Missing and 4 partials ⚠️
agentstack/packaging.py	27.27%	8 Missing ⚠️

📢 Thoughts on this report? Let us know!

[srilaasya]

Technically it creates a new llms.txt file in place of the existing one every time a workflow is run. But we're essentially just converting markdown to text-which doesn't necessarily capture all the guidelines to create an llms.txt file. Firecrawl has a new update where they're using Gemini to convert sites to llms.txt and it's good. Will raise a ticket to use that instead of existing workflow.