feat(secret): source at runtime

[dargmuesli]

Resolves #297

Quick draft to demonstrate what I intend to achieve. Collaboration welcome.

[codecov]

Codecov Report

Attention: 8 lines in your changes are missing coverage. Please review.

Comparison is base (c564106) 19.26% compared to head (eaca0dc) 19.43%.

Files	Patch %	Lines
src/runtime/nitro/utils/verify.ts	0.00%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #298      +/-   ##
==========================================
+ Coverage   19.26%   19.43%   +0.16%     
==========================================
  Files          12       12              
  Lines         493      494       +1     
  Branches       23       21       -2     
==========================================
+ Hits           95       96       +1     
  Misses        398      398              

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

[danielroe]

I don't think we should read file system at runtime - this wouldn't work in non-Node environments, for example. Is there a situation where defining the secret key in an environment variable wouldn't work?