fix: resolve all SonarQube issues and add coverage tests

[Otoru]

Summary

• Fix BLOCKER in observability/logger.py — correlation filter always returned True regardless of span validity
• Replace Union[X, None] with X | None across all CLI modules (SonarQube prefer modern union syntax)
• Reduce cognitive complexity in channel.py, protocol/base.py, protocol/reader_fsm.py, protocol/telemetry.py, group/ring.py, and observability/server.py by extracting focused helper methods
• Add sonar-project.properties for reproducible scanner configuration
• Add unit tests for: telemetry log helpers, reader FSM event-lock multi-part paths, and protocol base I/O EOF/error paths

Quality gate result

Metric	Before	After	Threshold
new_violations	40	0	0
new_coverage	—	94.2%	≥ 80%
new_duplicated_lines_density	—	0.87%	≤ 3%

All conditions: OK ✅

Test plan

• poetry run pytest — 242 passed
• poetry run black --check genesis/ tests/ examples/
• poetry run mypy