tests: regenerate affected snapshots after cycle 3 fixes

- empty_policies_renders_spec_violation_with_span: span now on labelValues key
- endpoint_mismatch_spec_violation: diagnostic code changed, span on raw endpoint string
- endpoint_only_no_did_skips_identity: summaries normalized to space-separated format
- plc_directory_unreachable_renders_network_error: no diagnostic body changes

All 12 integration tests pass; snapshots are semantically correct for updated fixes

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