Billing upgrade/downgrade, inviti in app e diretta YouTube da mobile.

Upgrade Stripe con addebito immediato; downgrade programmato a fine periodo.
UX billing più sobria con box info; icone piani. API inviti e OAuth YouTube
per staff trasmissione; deep link join; scelta partita programmata o nuova.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/views/public/clubs/billing.html.erb

@@ -6,6 +6,9 @@
   <%= render "shared/club_subscription_status", club: @club, entitlements: @entitlements, subscription: @subscription, on_billing_page: true %>
 
   <%= render "shared/stripe_secure_payment" %>
+  <% if MatchLiveTv.stripe_enabled? %>
+    <%= render "shared/plan_change_info", subscription: @subscription %>
+  <% end %>
   <%= render "shared/plan_cards", show_stripe_portal: false %>
   <%= render "shared/subscription_cancel", club: @club, subscription: @subscription %>
 

backend/app/views/public/invitations/show.html.erb

@@ -5,10 +5,17 @@
 <div class="card" style="max-width:480px">
   <h1>Accesso staff — <%= @invitation.team.name %></h1>
   <p>Sei stato aggiunto come <strong>responsabile trasmissione</strong> (<%= @invitation.email %>).</p>
+  <p class="muted" style="font-size:0.9rem;margin-bottom:16px">
+    Nell’app Match Live TV accedi con <strong><%= @invitation.email %></strong>, accetta l’invito e collega il tuo canale YouTube.
+  </p>
   <% if logged_in? %>
     <%= button_to "Accetta invito", public_invitation_path(token: @token), method: :post, class: "btn btn-primary" %>
   <% else %>
     <p><%= link_to "Accedi", public_login_path %> o <%= link_to "registrati", public_signup_path %> con <%= @invitation.email %>.</p>
     <%= button_to "Accetta (se già loggato)", public_invitation_path(token: @token), method: :post, class: "btn btn-secondary" %>
   <% end %>
+  <p style="margin-top:16px;font-size:0.88rem;color:#888">
+    App mobile:
+    <a href="matchlivetv://join/<%= @token %>">Apri invito nell’app</a>
+  </p>
 </div>

backend/app/views/public/teams/billing.html.erb

@@ -8,7 +8,7 @@
   <div class="plans">
     <% @plans.each do |plan| %>
       <div class="plan-card">
-        <h3><%= plan.name %></h3>
+        <%= render "shared/plan_title", plan: plan %>
         <% if plan.slug == "free" %>
           <div class="plan-price">€0</div>
         <% elsif plan.slug == "premium_light" %>
@@ -27,7 +27,6 @@
         <% if plan.slug == @entitlements.plan.slug %>
           <span class="btn btn-secondary" style="opacity:0.7">Piano attuale</span>
         <% elsif plan.slug == "free" %>
-          <p style="color:#888;font-size:0.85rem">Contatta il supporto per downgrade.</p>
         <% elsif MatchLiveTv.stripe_enabled? %>
           <%= link_to "Gestisci abbonamento società", public_club_billing_path(@team.club), class: "btn btn-primary" %>
         <% else %>