feat(config): let the operator turn off the breach and update checks

Two requests left the server without anything being connected: the
HaveIBeenPwned range query on every password set (registration, change,
admin reset) and the daily GitHub releases request behind the About page
and the admin version tile. Neither could be turned off, which made
"nothing leaves" untrue for an instance that wanted it to be.

PASSWORD_BREACH_CHECK_DISABLED and UPDATE_CHECK_DISABLED (1, true, yes or
on) stop each request. Both stay on by default. The breach check keeps
its fail-open contract: switched off, a password is simply not looked up.
The update route answers status "unknown" with reason "disabled" and
the admin tile says the check is off. The password routes reach the
check only through the switch, and a test holds that import line.

Both are on the compose whitelist, in the env manifest under a new
"Outbound requests" group with IP_GEO_LOOKUP_DISABLED, and documented in
both env examples and the getting-started guide.

src/app/api/admin/users/[id]/reset-password/route.ts

@@ -14,7 +14,7 @@ import { destroyAllSessions } from "@/lib/auth/session";
 import { revokeStepUpElevations } from "@/lib/auth/step-up";
 import { NextRequest, NextResponse } from "next/server";
 import { resolveServerLocale } from "@/lib/i18n/server-locale";
-import { checkPasswordBreach } from "@/lib/auth/hibp";
+import { checkPasswordBreachIfEnabled } from "@/lib/password-breach-check";
 import { getServerTranslator } from "@/lib/i18n/server-translator";
 
 export const POST = apiHandler(
@@ -70,7 +70,7 @@ export const POST = apiHandler(
 
     // v1.23 — reject an admin-set password found in a known breach corpus
     // (HIBP k-anonymity). Fail-open on an unreachable HIBP.
-    const breach = await checkPasswordBreach(password);
+    const breach = await checkPasswordBreachIfEnabled(password);
     if (breach?.breached) {
       return apiError(
         getServerTranslator(locale).t("auth.passwordBreached"),