refactor: Zod-based config loader

[fabiovincenzi]

Replace JSON-Schema with Zod for config validation and default injection
Add typed config export, loadConfig(), validate() and setConfigFile()
Update index.ts to use the new loader and pass the validated config.

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

Attention: Patch coverage is 83.70044% with 111 lines in your changes missing coverage. Please review.

Please upload report for BASE (main@fc6f166). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
src/config/index.ts	82.22%	8 Missing and 16 partials ⚠️
src/config/generated/config.ts	80.00%	13 Missing and 4 partials ⚠️
src/service/passport/oidc.js	18.75%	13 Missing ⚠️
src/service/passport/ldaphelper.js	26.66%	11 Missing ⚠️
src/service/routes/auth.js	86.84%	5 Missing ⚠️
src/config/ConfigLoader.ts	84.00%	2 Missing and 2 partials ⚠️
.../processors/push-action/checkUserPushPermission.ts	42.85%	4 Missing ⚠️
src/proxy/routes/index.ts	91.83%	3 Missing and 1 partial ⚠️
src/service/passport/activeDirectory.js	88.88%	4 Missing ⚠️
src/service/passport/jwtAuthHandler.js	84.61%	4 Missing ⚠️
... and 15 more

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #45   +/-   ##
=======================================
  Coverage        ?   78.51%           
=======================================
  Files           ?       57           
  Lines           ?     2378           
  Branches        ?      291           
=======================================
  Hits            ?     1867           
  Misses          ?      460           
  Partials        ?       51           

☔ 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.