Replace render_turbo_stream cancel handlers with form#cancel Stimulus action

Add cancel() method to form_controller that handles all close cases:
- tabular forms (<tr>): removes inner form, re-enables link, shows hidden row
- measurements create form: removes self, enables trigger link, shows no-items

Data attributes already present on controller elements (data-form, data-link,
data-hidden-row) drive the behaviour. Two extra attributes on the create form
(data-cancel-enable, data-cancel-show) cover the non-tabular case.

Delete now-unused _form_close and _edit_form_close partial templates.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/javascript/controllers/form_controller.js

@@ -22,4 +22,30 @@ export default class extends Controller {
       event.preventDefault()
     }
   }
+
+  cancel(event) {
+    event.preventDefault()
+    const el = this.element
+
+    // Move focus to next open form if this one had focus
+    const focused = document.activeElement
+    if (!focused || focused === document.body || el.contains(focused)) {
+      const next = el.parentElement?.querySelector(`#${el.id} ~ tr:has([autofocus])`)
+        ?? el.parentElement?.querySelector("tr:has([autofocus])")
+      next?.querySelector("[autofocus]")?.focus()
+    }
+
+    // Remove associated inner form element (tabular: <tr> wraps a separate <form>)
+    document.getElementById(el.dataset.form)?.remove()
+
+    // Re-enable trigger link
+    const enableId = el.dataset.link ?? el.dataset.cancelEnable
+    if (enableId) Turbo.StreamElement.prototype.enableElement(document.getElementById(enableId))
+
+    // Show hidden row (tabular forms) or no-items placeholder (create form)
+    document.getElementById(el.dataset.hiddenRow)?.removeAttribute("style")
+    document.getElementById(el.dataset.cancelShow)?.style.removeProperty("display")
+
+    el.remove()
+  }
 }

app/views/measurements/_edit_form.html.erb

@@ -19,7 +19,7 @@
       <%= form.button %>
       <%= image_link_to t(:cancel), "close-outline", measurements_path,
         class: 'dangerous', name: :cancel,
-        onclick: render_turbo_stream('edit_form_close', {row: row}) %>
+        data: {action: 'click->form#cancel'} %>
     </td>
   <% end %>
 <% end %>

app/views/measurements/_edit_form_close.html.erb

@@ -1,2 +0,0 @@
-<%= turbo_stream.close_form row %>
-<%= turbo_stream.update :flashes %>

app/views/measurements/_edit_panel.html.erb

@@ -26,7 +26,7 @@
           <%= form.button %>
           <%= image_link_to t(:cancel), "close-outline", measurements_path,
             class: 'dangerous', name: :cancel,
-            onclick: render_turbo_stream('edit_form_close', {row: row}) %>
+            data: {action: 'click->form#cancel'} %>
         </td>
       <% end %>
     </tbody>

app/views/measurements/_form.html.erb

@@ -1,6 +1,8 @@
 <%= tabular_form_with model: Measurement.new, id: :measurement_form,
   class: 'topside-area flex vertical center',
-  html: {data: {controller: 'form', action: 'keydown->form#processKey'}} do |form| %>
+  html: {data: {controller: 'form', action: 'keydown->form#processKey',
+                cancel_enable: 'new_measurement_link',
+                cancel_show: 'no_items'}} do |form| %>
 
   <table class="items-table center">
     <tbody id="readouts">
@@ -34,6 +36,6 @@
   <div class="flex reverse">
     <%= form.button id: :create_measurement_button, disabled: true -%>
     <%= image_link_to t(:cancel), "close-outline", measurements_path, name: :cancel,
-      class: 'dangerous', onclick: render_turbo_stream('form_close') %>
+      class: 'dangerous', data: {action: 'click->form#cancel'} %>
   </div>
 <% end %>

app/views/measurements/_form_close.html.erb

@@ -1,4 +0,0 @@
-<%= turbo_stream.update :flashes %>
-<%= turbo_stream.remove :measurement_form %>
-<%= turbo_stream.show :no_items -%>
-<%= turbo_stream.enable :new_measurement_link -%>

app/views/quantities/_form.html.erb

@@ -18,7 +18,7 @@
     <td class="flex">
       <%= form.button %>
       <%= image_link_to t(:cancel), "close-outline", quantities_path, class: 'dangerous',
-        name: :cancel, onclick: render_turbo_stream('form_close', {row: row}) %>
+        name: :cancel, data: {action: 'click->form#cancel'} %>
     </td>
     <td></td>
   <% end %>

app/views/quantities/_form_close.html.erb

@@ -1,2 +0,0 @@
-<%= turbo_stream.close_form row %>
-<%= turbo_stream.update :flashes %>

app/views/units/_form.html.erb

@@ -16,7 +16,7 @@
     <td class="flex">
       <%= form.button %>
       <%= image_link_to t(:cancel), "close-outline", units_path, class: 'dangerous',
-        name: :cancel, onclick: render_turbo_stream('form_close', {row: row}) %>
+        name: :cancel, data: {action: 'click->form#cancel'} %>
     </td>
     <td></td>
   <% end %>

app/views/units/_form_close.html.erb

@@ -1,2 +0,0 @@
-<%= turbo_stream.close_form row %>
-<%= turbo_stream.update :flashes %>