Update forge-demo hello HTML to Forge Software Factory

Goal

Small web-service change: update the forge-demo hello ConfigMap HTML so the public demo greets visitors with copy from "Forge Software Factory" (Slack operator request). Worker implements after plan approval; humans merge; Argo syncs steady state.

Acceptance criteria

• PR opened against main that changes k8s/apps/forge-demo-hello hello-html copy to greet from "Forge Software Factory"
• Review checklist completed before merge
• After merge, Argo Application forge-demo-hello Healthy/Synced
• curl -fsS https://localpower.diegobarahona.com | grep -q "Forge Software Factory"