feat: add evals for RECOMMENDATION format, session awareness, and enum completeness

Free tests (Tier 1): RECOMMENDATION format + session awareness in all
preamble SKILL.md files, enum completeness checklist structure and CRITICAL
classification.

E2E eval: /review catches missed enum handlers when a new status value
is added but not handled in case/switch and notify methods.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

test/fixtures/review-eval-enum-diff.rb

@@ -0,0 +1,30 @@
+# Feature branch version: adds "returned" status but misses consumers
+class Order < ApplicationRecord
+  STATUSES = %w[pending processing shipped delivered returned].freeze
+
+  validates :status, inclusion: { in: STATUSES }
+
+  def display_status
+    case status
+    when 'pending'    then 'Awaiting processing'
+    when 'processing' then 'Being prepared'
+    when 'shipped'    then 'On the way'
+    when 'delivered'  then 'Delivered'
+    # BUG: 'returned' not handled — falls through to nil
+    end
+  end
+
+  def can_cancel?
+    # BUG: should 'returned' be cancellable? Not considered.
+    %w[pending processing].include?(status)
+  end
+
+  def notify_customer
+    case status
+    when 'pending'    then OrderMailer.confirmation(self).deliver_later
+    when 'shipped'    then OrderMailer.shipped(self).deliver_later
+    when 'delivered'  then OrderMailer.delivered(self).deliver_later
+    # BUG: 'returned' has no notification — customer won't know return was received
+    end
+  end
+end