feat: add support for watching pods across multiple namespaces

[blink-so]

This PR addresses issue #5 by adding support for watching pods across multiple namespaces or all namespaces.

Changes

Core Functionality

• Multi-namespace support: When namespace is empty, the application now watches pods in all namespaces
• Backward compatibility: When a specific namespace is provided, behavior remains unchanged (single namespace)
• Conditional RBAC: Automatically uses ClusterRole/ClusterRoleBinding for all namespaces, Role/RoleBinding for single namespace

Implementation Details

• Modified informer factory creation to conditionally include WithNamespace() option
• Updated Helm chart to create appropriate RBAC resources based on namespace configuration
• Enhanced logging to clearly indicate whether watching all namespaces or a specific one

Documentation

• Updated README.md with multi-namespace usage examples
• Enhanced values.yaml documentation explaining the new behavior
• Added clear examples for both single and multi-namespace deployments

Use Cases

This enables several important deployment patterns:

• Per-user namespaces: Single logstream deployment can monitor workspaces across user-specific namespaces
• Multi-tenant environments: Better resource isolation while maintaining centralized log streaming
• Flexible RBAC: Automatic permission scoping based on deployment configuration

Testing

• Code compiles successfully
• Maintains backward compatibility with existing single-namespace deployments
• Helm chart generates correct RBAC resources for both scenarios

Breaking Changes

None - this is fully backward compatible. Existing deployments will continue to work exactly as before.

[ericpaulsen]

re-writing via updated Blink.