doc: fix bare (class Eq) → (class prelude.Eq) in operator-routing-eq-ord spec north-star

Fieldtest (505eb84) finding spec_gap → tighten-the-design-ledger:
the spec's §"Concrete code shapes" north-star example at line 113
wrote `(class Eq)` (bare). An LLM-author who copies the spec
verbatim hits `bare-cross-module-class-ref` — the language
requires `(class prelude.Eq)` (qualified) at instance-declaration
sites. The shipped fixture `examples/eq_user_adt_smoke.ail`
already uses the qualified form (line 5 — implementer caught the
drift during Task 1 fixture authoring), so the corpus was
consistent; only the spec text drifted. Fix: rewrite line 113
to match the qualified form the language and the existing
corpus require.

One-line doc fix; no code surface change. Spec stays as
`docs/specs/2026-05-20-operator-routing-eq-ord.md` (Status: Draft
unchanged — content correction, not a re-issue).

docs/specs/2026-05-20-operator-routing-eq-ord.md

@@ -110,7 +110,7 @@ follow: lit patterns inherit equality dispatch by construction.
   (data Point
     (ctor Point (con Int) (con Int)))
   (instance
-    (class Eq)
+    (class prelude.Eq)
     (type (con Point))
     (method eq
       (body (lam (params (typed p1 (con Point)) (typed p2 (con Point))) (ret (con Bool))