Respect logging.output at startup and avoid counting discovery cancellation as endpoint failure

[sg-shag]

Summary

Observed two operational issues while running Olla behind frontend/edge services:

1. logging.output from config was not applied during startup because logger initialization happened before config load.
2. Discovery cancellation during coordinated shutdown/restart (context.Canceled) was treated as a regular discovery failure, which could incorrectly contribute to failure state.

Expected behavior

• Logger should honor configured logging.output path/stream at startup.
• Discovery cancellation caused by lifecycle shutdown should be treated as expected and not counted as endpoint failure.

Proposed changes

• Load config before logger initialization in main.go, and build logger settings from loaded config.
• Add explicit logger OutputPath handling for absolute/relative output file targets.
• In discovery service, short-circuit context.Canceled and skip failure-count increment/disable path for that case.
• Add test coverage proving cancellation does not increment failures or disable endpoint.

Files touched

• main.go
• internal/logger/logger.go
• internal/adapter/discovery/service.go
• internal/adapter/discovery/service_test.go