refactor: Make brand-sample one layer simpler

[kdmccormick]

This collapses brand-sample/src into brand-sample. The extra layer did not seem to be serving a purpose; it actually confused me over and over again when I was copying files around to debug tutor-contrib-paragon :P

This also drops the Makefile and merges its on rule (build) into
package.json, removing the unnecessary package.json->Makefile->package.json
indirection that was going on.

No AI use.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.04%. Comparing base (ccc9a1d) to head (7d52bf5).

Additional details and impacted files

@@ Coverage Diff @@## main #49 +/- ##
=======================================
Coverage 93.04% 93.04% =======================================
Files 16 16 Lines 503 503 Branches 18 18 =======================================
Hits 468 468 Misses 24 24 Partials 11 11 

Flag	Coverage Δ
unittests	93.04% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[brian-smith-tcril]

I think this was needed because of the top-level .gitignore in this repo. Removing it won't break anything, but if someone were to delete the dist dir and commit the removal we'd need to force-add it to get it back.

sample-plugin/.gitignore

Line 13 in ccc9a1d

dist/

[kdmccormick]

right, fixed, thanks

[brian-smith-tcril]

Overall this makes sense. The only real benefit to having the package live in a src subdir was not having the output of builds tied to the checked-in dist.