Actionable v1.8.1 — housekeeping

Housekeeping. The Actionable/VerbNotLast cop resolves superclass names the way
Ruby does, so same-named classes in one file no longer confuse it; the
UPGRADING.md drift guard is fixture-tested and now asks for an explicit
decision on every visible CHANGELOG entry. No runtime behaviour changes.

Changed

• Actionable/VerbNotLast resolves a superclass by its lexical full name.
  It matched by the last name segment, so in one file module B; class Base; end; class X < Base counted as an action when module A held a Base < Actionable::Action, and a file's own Legacy::ApplicationAction counted as
  the listed base. It now looks the name up as Ruby does (enclosing module /
  class outwards, a compact class A::B opens only A::B, ::X is the
  top level), so those classes are left alone, and a listed full name is
  found from inside its namespace (module Ops; class X < BaseAction with
  Ops::BaseAction listed). An offense it newly reports is a call the
  first-run check already raises on.

Tests / CI

• The UPGRADING.md drift guard asks for a decision on every visible
  change. Each [Unreleased] bullet under ### Changed, ### Removed or
  ### Breaking… must carry an upgrading: <slug> marker comment (with its
  guide entry, as before) or upgrading: none, so a change filed there
  without an upgrade note no longer slips past it. Released sections are not
  re-checked. The guard's own examples now run on fixtures, so they hold in
  any release state; one example still checks the live files.