fix: addon JSON pointers

[jolheiser]

This PR fixes some issues I ran into when creating an addon forge.

• 28af9ba fixes some pointer dereference issues when unmarshaling JSON
• 6211f04 moves a trace log outside an if-check. Not strictly necessary, but was slightly confusing before when debugging
• 19936f6 makes a minor correction to the docs for the woodpecker module

[woodpecker-bot]

Deployment of preview was torn down

[codecov]

Codecov Report

Attention: Patch coverage is 10.00000% with 9 lines in your changes missing coverage. Please review.

Project coverage is 28.18%. Comparing base (db45794) to head (19936f6).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
server/forge/addon/server.go	0.00%	7 Missing ⚠️
server/forge/addon/client.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4508      +/-   ##
==========================================
- Coverage   28.20%   28.18%   -0.02%     
==========================================
  Files         397      397              
  Lines       28158    28158              
==========================================
- Hits         7941     7936       -5     
- Misses      19512    19517       +5     
  Partials      705      705              

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