refactor: simplify batch (S-02 to S-04)

Three small reuse wins from the W6 simplify review:

- openapi/registry.ts swaps the lazy require() for a static import.
  The ESLint disable + as-cast carried no real benefit; the only
  callers always loaded the route table anyway.
- Extract useCoachPrefs() into a shared hook so the settings sheet
  and message thread share one queryKey + one fallback shape. Removes
  the drift between the two existing inline blocks.
- Replace the 9-deep wantsX boolean ladder in coach snapshot with a
  single CoachScopeSource -> MeasurementType[] map. Drives both the
  WHERE type IN (...) build and the appleHealthBlocks gate, so adding
  a new metric is one entry instead of three parallel edits.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/hooks/use-coach-prefs.ts

@@ -0,0 +1,36 @@
+"use client";
+
+import { useQuery } from "@tanstack/react-query";
+
+import {
+  DEFAULT_COACH_PREFS,
+  type CoachPrefs,
+} from "@/lib/validations/coach-prefs";
+
+/**
+ * v1.4.23 W6 (S-03) — shared accessor for the per-user Coach
+ * preferences row. Both the Coach drawer's settings sheet and the
+ * message-thread evidence-disclosure default consume the same
+ * `/api/auth/me/coach-prefs` payload; before the extraction the two
+ * call sites duplicated the same `useQuery` block with subtly
+ * different fallback semantics (one threw on `!ok`, the other returned
+ * defaults). The hook centralises the cache key, the envelope unwrap,
+ * and the "treat fetch failure as defaults" stance so the next surface
+ * (insights cog, settings tab) inherits a single source of truth.
+ *
+ * The query is gated on `enabled` so the settings sheet can defer the
+ * fetch until the sheet actually opens. Callers that always want the
+ * row (message thread) leave it unset (defaults to true).
+ */
+export function useCoachPrefs(opts?: { enabled?: boolean }) {
+  return useQuery<CoachPrefs>({
+    queryKey: ["coach-prefs"],
+    queryFn: async () => {
+      const res = await fetch("/api/auth/me/coach-prefs");
+      if (!res.ok) return DEFAULT_COACH_PREFS;
+      const env = (await res.json()) as { data: CoachPrefs };
+      return env.data;
+    },
+    enabled: opts?.enabled,
+  });
+}