bootstrap: swap BS4 (alexwine) CSS for bootstrap@5 npm

Completes the Bootstrap 4->5 migration now that every jQuery/BS4 widget is React
(navbar, carousel, dropdowns) — plus the feedback toggle here (Feedback.js:
global `$('#feedback-form').toggle()` -> React state).

- Load Bootstrap 5 CSS from the `bootstrap` npm package in client/index.js
  (imported first so app + component styles and react-bootstrap override it).
- Remove the `alexwine:bootstrap-4` meteor package (BS4 CSS + jQuery + BS4 JS).
  jQuery for jquery-validation still comes from the npm `jquery` dep.
- Utility renames to BS5: ml-auto->ms-auto, float-right->float-end,
  btn-block->w-100, data-toggle->data-bs-toggle (FromNow tooltip).
- forms.scss `.form-label` is no longer a shim (BS5 ships it); comment updated.

Full-app build boots clean; server suite 36 passing. Needs a visual staging pass
across all pages (BS4->5 shifts grid gutters/typography); forms should improve
since react-bootstrap v2 already emitted BS5 markup.

imports/startup/client/index.js

@@ -1,4 +1,8 @@
 /* global */
+// Bootstrap 5 CSS (npm) replaces the old `alexwine:bootstrap-4` meteor package.
+// Import it first so the app + component stylesheets below (and react-bootstrap,
+// which targets BS5) override it.
+import 'bootstrap/dist/css/bootstrap.css';
 import React from 'react';
 import { createRoot } from 'react-dom/client';
 import { HelmetProvider } from 'react-helmet-async';