feat(readmymind): alternates row, phone accessory key, phone-sized modal (phase 3 part 1)

The Read My Mind modal grows up and reaches phones:

- Alternate suggestions (the predictor's verify/redirect kinds) now render
  as tappable rows below the main field. Tapping one swaps it into the
  editable field; the edit you were making folds back into the row you
  leave, so toggling between alternates never loses typing. Rethink now
  records the WHOLE shown set (main + alternates) as rejected.
- Phones get a 🧠 key on the keyboard accessory bar (both simple and
  extended layouts), gated on the same synced readMyMindEnabled setting
  via an rmm-enabled marker class on the BAR element: setMode() rebuilds
  the buttons' innerHTML, so per-key state would be wiped. Synced at init
  and re-synced by applyHeaderVisibilitySettings() on every settings
  apply, so a live toggle needs no reload. The header button stays off
  phones.
- On phones the modal renders as a small dialog (mirrors modal-sm) instead
  of the full-screen default, with wrap-friendly finger-sized footer
  buttons. Not modal-sm itself: that caps desktop width at 340px and this
  modal wants 560px there.
- On touch devices the ready/swap paths no longer focus the field, so the
  OS keyboard does not pop over the alternates that just rendered.
- New static guard test/readmymind-phone-key.test.ts pins the dual-template
  key, the marker-class gating, the phone-hidden header button, the
  small-dialog phone modal, and the no-innerHTML discipline.

Part 2 of phase 3 (rethink steering, the free-text steer note) is next;
the API already accepts steer.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/web/public/index.html

@@ -2813,6 +2813,7 @@
             <input type="text" id="readMyMindPrompt" class="readmymind-prompt-input" data-i18n-skip aria-label="Predicted prompt, editable" onkeydown="if(event.key==='Enter')app.sendReadMyMind(true)">
           </div>
           <div class="readmymind-why" id="readMyMindWhy" data-i18n-skip></div>
+          <div class="readmymind-alternates" id="readMyMindAlternates" data-i18n-skip style="display:none"></div>
         </div>
         <div class="readmymind-error" style="display:none">No suggestion this time. Rethink to try again.</div>
       </div>