Add bns logs command for streaming container logs (#72)

* Add bns logs command for streaming container logs

Implement a new top-level 'bns logs' command that streams container application
logs (stdout/stderr) from Kubernetes pods with support for multi-component
streaming and multiple output formats.

Features:
- Stream logs from single or multiple components
- Environment-wide log streaming (--environment flag)
- Component filtering by ID or name (--name flag)
- Context fallback support
- kubectl-compatible flags (--follow, --tail, --since, --timestamps, etc.)
- Thread-safe merged output from multiple sources
- Color-coded prefixes for easy identification [component/pod/container]
- Multiple output formats: stylish (default), JSON, YAML
- Graceful error handling and signal interruption (Ctrl+C)

New files:
- cmd/logs/root.go - Main command implementation with component resolution
- pkg/k8s/kubectl/logs/logs.go - K8s log streaming wrapper
- pkg/k8s/kubectl/logs/multiplexer.go - Concurrent streaming coordinator

Modified files:
- cmd/utils/root.go - Register logs command

Usage examples:
  bns logs --environment env-123 --follow --tail 100
  bns logs --component comp-1,comp-2 --follow
  bns logs --environment env-123 --name api --name worker -o json
  bns logs --component comp-123 --since 5m --timestamps

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

* Fix: Remove exec command import (belongs to separate PR)

* Fix duplicate Flags section in logs help output

- Move examples from Long to Example field for proper Cobra formatting
- Remove manual Flags documentation from Long field
- Let Cobra automatically generate the Flags section
- Improves help readability by eliminating duplication

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Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: alexo-bunnyshell