#1739 fix(k3s): satisfy statix and clean up spec after #1738

Summary

#1738 auto-merged before the slower checks completed, so two failures landed on main:

• nix-lint (statix): galacticaAuthorizedKey = galacticaAuthorizedKey; should use inherit.
• shell-test: a placeholder-guard grep test in spec/activate_k3s_spec.sh had over-escaped regex and shellspec marked it WARNED, which fails the suite. The behavior is already covered by a functional test in the same describe block, so just remove it.

Test plan

• shellspec spec/activate_k3s_spec.sh -> 15 examples, 0 failures
• statix check config/k3s/default.nix clean

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Summary by cubic

Unblocks CI after #1738 by fixing a statix lint and removing a redundant test in the k3s activation spec. Uses inherit for galacticaAuthorizedKey and drops an over-escaped grep test already covered elsewhere.

• Bug Fixes
  • Use inherit galacticaAuthorizedKey; in config/k3s/default.nix to satisfy statix.
  • Remove redundant placeholder-guard grep test from spec/activate_k3s_spec.sh to eliminate WARN and keep the suite green.