Covers content/health.py (get_template_stats, get_template_freshness,
get_content_gaps, check_hreflang_orphans, check_missing_build_files,
check_broken_scenario_refs, get_all_health_issues) and all 6 routes in
admin/pseo_routes.py (dashboard, health partial, gaps partial, generate
gaps, jobs list, job status polling).
Also fixes two bugs found while writing tests:
- check_hreflang_orphans: was grouping by url_path, but EN/DE articles
have different paths. Now extracts natural key from slug pattern
"{template_slug}-{lang}-{nk}" and groups by nk.
- pseo_job_status.html + pseo_jobs.html: | default('') | truncate() fails
when completed_at is None (default() only handles undefined, not None).
Fixed to (value or '') | truncate().
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
