refactor(jobengine): delete TaskRunner service

- Remove TaskRunner source, tests, libraries (3 directories)
- Remove from compose, services-matrix, nginx, hosts, smoke tests
- Remove CLI commands, UI references, Authority scopes
- Remove docs, OpenAPI spec, QA state files
- Leave task_runner_id DB columns as nullable legacy
- PacksRegistry preserved (independent service)
- Eliminates 2 containers (taskrunner-web + taskrunner-worker)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

devops/compose/openapi_routeprefix_smoke_microservice.csv

@@ -89,7 +89,7 @@
 "Microservice","/vexhub","https://vexhub.stella-ops.local","/vexhub/api/v1/vex/index","200"
 "Microservice","/vexlens","http://vexlens.stella-ops.local","/vexlens/api/v1/vexlens/stats","200"
 "Microservice","/orchestrator","http://orchestrator.stella-ops.local","/orchestrator/scale/load","200"
-"Microservice","/taskrunner","http://taskrunner.stella-ops.local","/taskrunner","302"
+
 "Microservice","/cartographer","http://cartographer.stella-ops.local",,
 "Microservice","/reachgraph","http://reachgraph.stella-ops.local","/reachgraph/v1/cve-mappings/stats","400"
 "Microservice","/doctor","http://doctor.stella-ops.local","/doctor/api/v1/doctor/checks","401"