chore: remove arghda-core/ subtree + cross-refs (extracted to standalone repo per #159) #267

Job	Run time
governance / Trusted-base reduction policy	6s
governance / Well-Known (RFC 9116 + RSR)	6s
governance / Licence consistency	6s
governance / Language / package anti-pattern policy	13s
governance / Code quality + docs	11s
governance / Workflow security linter	4s
governance / Security policy checks	4s
governance / Guix primary / Nix fallback policy	4s
governance / Validate Hypatia baseline	3s
	57s

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