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/ui/components/OAuthLoginButton/OAuthLoginButton.js

@@ -45,7 +45,7 @@ const defaultCallback = (error) => {
 
 const OAuthLoginButton = ({ service, callback = defaultCallback }) => (
   <button
-    className={`btn btn-block btn-raised btn-danger OAuthLoginButton OAuthLoginButton-${service}`}
+    className={`btn w-100 btn-raised btn-danger OAuthLoginButton OAuthLoginButton-${service}`}
     type="button"
     onClick={() => handleLogin(service, callback)}
   >