fix(goals/pledge-modal): helper text reacts to selected account

The helper paragraph above the amount field was painted off
`@goal.any_connected_account?` — a goal-level decision that fires
once at modal render and never updates. On a mixed-funding goal
(one connected + one manual account linked), the helper read the
"transfer" copy regardless of which account the user picked from
the dropdown, even though the saved pledge's `kind` is decided
per-account by `kind_for_account` in the controller. Stale UI vs.
correct data.

Render both helper paragraphs hidden, then toggle the right one
visible via Stimulus on `change->goal-pledge-preview#accountChanged`.
The select renders its `<option>` tags with `data-manual="true|false"`
from `Account#manual?`; the controller reads that attribute off
the currently-selected option and flips `hidden` on the two helper
targets.

`connect()` also calls `accountChanged()` so the initial paint
matches the preselected account from `?account_id=…` (the catch-up
callout's amount-specific deep link).

Switch from `options_from_collection_for_select` to
`options_for_select` with the `[label, value, { data: { manual: } }]`
3-tuple form — Rails supports per-option data attributes there but
not on the collection helper.

app/javascript/controllers/goal_pledge_preview_controller.js

@@ -4,7 +4,13 @@ import { Controller } from "@hotwired/stimulus";
 // target amount from values and updates a preview sentence each keystroke.
 // Template strings come from ERB so the wording stays localized.
 export default class extends Controller {
-  static targets = ["amountInput", "preview"];
+  static targets = [
+    "amountInput",
+    "preview",
+    "accountSelect",
+    "helperConnected",
+    "helperManual",
+  ];
   static values = {
     currentBalance: Number,
     targetAmount: Number,
@@ -16,6 +22,22 @@ export default class extends Controller {
 
   connect() {
     this.update();
+    this.accountChanged();
+  }
+
+  // Helper text reacts to the currently-selected account, not the goal as a
+  // whole. A mixed-funding goal (one connected account + one manual) used to
+  // paint the "connected" helper even if the user then picked the manual
+  // account from the dropdown — the saved pledge would be `kind: manual_save`
+  // (correct, per `kind_for_account` in the controller) but the helper read
+  // "transfer-style" copy until submission.
+  accountChanged() {
+    if (!this.hasAccountSelectTarget) return;
+    if (!this.hasHelperConnectedTarget || !this.hasHelperManualTarget) return;
+    const opt = this.accountSelectTarget.selectedOptions[0];
+    const isManual = opt?.dataset.manual === "true";
+    this.helperConnectedTarget.hidden = isManual;
+    this.helperManualTarget.hidden = !isManual;
   }
 
   update() {

app/views/goal_pledges/new.html.erb

@@ -5,6 +5,12 @@
       <%= render "shared/form_errors", model: @pledge %>
     <% end %>
 
+    <%
+      account_options = @goal.linked_accounts.map do |a|
+        [ a.name, a.id, { data: { manual: a.manual?.to_s } } ]
+      end
+    %>
+
     <%= styled_form_with model: @pledge,
                          url: goal_pledges_path(@goal),
                          class: "space-y-3",
@@ -17,12 +23,15 @@
                            goal_pledge_preview_template_nonzero_value: t(".preview_nonzero"),
                            goal_pledge_preview_template_reached_value: t(".preview_reached")
                          } do |f| %>
-      <p class="text-sm text-secondary">
-        <% if @goal.any_connected_account? %>
-          <%= t(".helper_transfer") %>
-        <% else %>
-          <%= t(".helper_manual") %>
-        <% end %>
+      <p class="text-sm text-secondary"
+         data-goal-pledge-preview-target="helperConnected"
+         hidden>
+        <%= t(".helper_transfer") %>
+      </p>
+      <p class="text-sm text-secondary"
+         data-goal-pledge-preview-target="helperManual"
+         hidden>
+        <%= t(".helper_manual") %>
       </p>
 
       <%= f.money_field :amount,
@@ -39,8 +48,14 @@
          data-goal-pledge-preview-target="preview"></p>
 
       <%= f.select :account_id,
-                   options_from_collection_for_select(@goal.linked_accounts, :id, :name, @pledge.account_id),
-                   { label: t(".account_label") } %>
+                   options_for_select(account_options, @pledge.account_id),
+                   { label: t(".account_label") },
+                   {
+                     data: {
+                       goal_pledge_preview_target: "accountSelect",
+                       action: "change->goal-pledge-preview#accountChanged"
+                     }
+                   } %>
 
       <div class="flex justify-end pt-2">
         <%= f.submit t(".submit") %>