fix: return code in CompileAndPublish rather than handleError

[ecrupper]

It'll be easier to follow that CompileAndPublish errors are returned with a code to handle rather than handle them itself.

I also made all the responses match across create, restart, and PostWebhook:

• 200 = skipped
• 201 = created
• 400 = bad request
• 401 = unauthorized owner
• 404 = missing resource
• 429 = build limit reached
• 500 = error processing or server unreachable

Open to suggestions on that, but the inconsistencies should be addressed at least.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 27 lines in your changes are missing coverage. Please review.

Project coverage is 65.33%. Comparing base (04f9308) to head (aa0b87e).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1107      +/-   ##
==========================================
+ Coverage   65.22%   65.33%   +0.11%     
==========================================
  Files         371      371              
  Lines       11961    11940      -21     
==========================================
  Hits         7801     7801              
+ Misses       3657     3636      -21     
  Partials      503      503              

Files	Coverage Δ
api/build/restart.go	0.00% <0.00%> (ø)
api/build/create.go	0.00% <0.00%> (ø)
api/build/compile_publish.go	0.00% <0.00%> (ø)