Add wide view and inline editing to Measurements page

The Measurements page gains a compact/wide view toggle (persisted in
localStorage). The wide view is a pivot table: rows = time points,
columns = quantity names (alphabetical), cells = value + delete button.

Clicking a value in either view opens an inline edit panel (Turbo Stream)
without leaving the page. The panel shows the quantity name, value input,
unit selector, taken_at picker, and Update/Cancel buttons.

Changes:
- MeasurementsController: add edit/update actions; order by taken_at desc
- measurements/index: compact table + wide container, view-toggle buttons
- measurements/_readout: data-* attributes for JS pivot builder; edit link
- measurements/_edit_panel, _edit_form, _edit_form_close,
  edit.turbo_stream, update.turbo_stream: inline edit views
- application.js: groupMeasurements, buildWideTable (alphabetical cols),
  getMeasurementsView / setMeasurementsView, editMeasurementWide,
  readoutUnitChanged, setDefaultUnit
- application.css: compact/wide visibility rules, .wide-cell flex layout,
  button.link reset, .items-table .form td alignment
- Pictograms: view-rows.svg, view-columns.svg (view-toggle icons)
- Locale: view_compact/view_wide toggle labels, edit link, update.success
- Tests: system tests for compact inline edit and wide view edit panel

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

app/views/measurements/_edit_form.html.erb

@@ -0,0 +1,24 @@
+<%= tabular_fields_for @readout, form: form_tag do |form| %>
+  <%- tag.tr id: row, class: "form", onkeydown: "formProcessKey(event)",
+    data: {form: form_tag, hidden_row: hidden_row, link: link} do %>
+    <td><%= @readout.quantity %></td>
+    <td class="ralign">
+      <%= form.number_field :value, required: true, autofocus: true %>
+    </td>
+    <td>
+      <%= form.collection_select :unit_id, @user_units, :id,
+        ->(u){ sanitize('&emsp;' * (u.base_id? ? 1 : 0) + u.symbol) },
+        {}, required: true %>
+    </td>
+    <td>
+      <%= form.datetime_field :taken_at %>
+    </td>
+    <td></td>
+    <td class="flex">
+      <%= form.button %>
+      <%= image_link_to t(:cancel), "close-outline", measurements_path,
+        class: 'dangerous', name: :cancel,
+        onclick: render_turbo_stream('edit_form_close', {row: row}) %>
+    </td>
+  <% end %>
+<% end %>