fix: Improve error handling and internationalization

[thomas-vilte]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 61.90476% with 24 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
internal/services/commit_service.go	65.51%	10 Missing ⚠️
...tructure/ai/gemini/gemini_pr_summarizer_service.go	0.00%	8 Missing ⚠️
...nternal/infrastructure/ai/gemini/gemini_service.go	60.00%	4 Missing ⚠️
cmd/main.go	0.00%	1 Missing ⚠️
...ernal/infrastructure/factory/pr_service_factory.go	0.00%	1 Missing ⚠️

Files with missing lines	Coverage Δ
internal/services/pr_service.go	100.00% <100.00%> (ø)
cmd/main.go	0.00% <0.00%> (ø)
...ernal/infrastructure/factory/pr_service_factory.go	0.00% <0.00%> (ø)
...nternal/infrastructure/ai/gemini/gemini_service.go	77.77% <60.00%> (-1.62%)	⬇️
...tructure/ai/gemini/gemini_pr_summarizer_service.go	0.00% <0.00%> (ø)
internal/services/commit_service.go	73.23% <65.51%> (-5.34%)	⬇️