Start on use_claude_code()

[hadley]

Fixes #2195

Note that something seems wrong with the permissions — claude still asks me if it's ok to edit various files and run Rscript. But it does grep and ls without confirmation.

[jennybc]

Suggested change

	"WebFetch(domain:github.com)"
	"WebFetch(domain:github.com)",
	"WebFetch(domain:raw.githubusercontent.com)"

I also end up with this one in most projects.

Other candidates I've accrued in local settings recently that might be generally useful (Claude 🫶 the gh cli):

...
      "Bash(cat:*)",
      "Bash(git grep:*)",
      "Bash(gh pr view:*)",
      "Bash(gh issue view:*)",
      "Bash(gh api:*)",
      "Bash(gh pr diff:*)",
      "Bash(gh issue list:*)",
      "WebFetch(domain:cran.r-project.org)",
...

We should probably regard inst/claude/settings.json as the main source of truth, then that will propagate to usethis's .claude/settings.json by applying use_claude_code() to itself.

[hadley]

Need something for news — i.e. alphbaetise by function name, and should be single line. Alphabetically order.

Do we need to explicitly allow skills?