v0.12.97: @newsroom.writer: agent decision policies, a series in four parts

Four new articles, joined by the new trail decision-policy:

1. Three policies for an agent: behaviour, decision and workflow, where they meet, zooming into one ABP cell, and four states for every element: defined, implemented, enforced, observed.
2. Approve at altitude: decisions at every altitude, signed off once and inherited below; a lower level may narrow the one above and never widen it, checked against declared envelopes.
3. Case law for agents: the shape of precedent in England and Wales applied to agents, the decision record as a law report, and how a decision earns its way into code.
4. Three decisions, mapped: memory deletion in the SGit adapter for Ruflo, this newsroom's release, and an illustrative refund, element by element.

The legal and governance facts were checked against primary sources: the UNISON judgment, the 1966 Practice Statement as described in Knauer, Pepper v Hart as restated in R (O), the UK Corporate Governance Code's Principle O, ISO Guide 73, OMG's DMN page and Sutton and Barto. Four figures use the new dn- prefix.