doc: update design document to reflect actual implementation

Update the kubernetes-conditions-integration.md design document to
reflect the actual implementation details:

- Add SriovNetworkNodePolicy as a supported CRD
- Add drain-specific conditions (DrainProgressing, DrainDegraded, DrainComplete)
- Document all condition reasons with actual constant names
- Add NetworkStatus shared type used by network CRDs
- Document pkg/status package with Patcher interface and transition detection
- Add ConditionsEqual helper function documentation
- Update API extension examples with actual struct definitions
- Add matchedNodeCount/readyNodeCount to Policy and PoolConfig status
- Add kubectl output examples showing new columns
- Update implementation commits list
- Mark document status as 'implemented'

Signed-off-by: Sebastian Sch <sebassch@gmail.com>

Author: SchSeba