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/assets/stylesheets/application.css

@@ -36,6 +36,7 @@
   --color-blue: #009ade;
   --color-dark-red: #b21237;
   --color-red: #ff1f5b;
+  --color-purple: #8b2be2;
 
   --depth: 0;
 
@@ -231,6 +232,10 @@ textarea:invalid {
   text-decoration: underline 1px var(--color-border-gray);
   text-underline-offset: 0.25em;
 }
+button.link {
+  border: none;
+  padding: 0;
+}
 [name=cancel],
 .auxiliary {
   border-color: var(--color-border-gray);
@@ -252,6 +257,13 @@ textarea:invalid {
   background-color: var(--color-red);
   border-color: var(--color-red);
 }
+tr:has(select[data-changed]) button[name="button"],
+.set-default-unit:not([disabled]) {
+  background-color: var(--color-purple);
+  border-color: var(--color-purple);
+  color: white;
+  fill: white;
+}
 .link:focus-visible {
   text-decoration-color: var(--color-gray);
 }
@@ -361,7 +373,7 @@ header {
   pointer-events: auto;
 }
 .flash:before {
-  filter: invert();
+  filter: invert(100%);
   height: 1.4em;
   margin: 0 0.5em;
   width: 1.4em;
@@ -513,7 +525,7 @@ header {
   cursor: grab;
 }
 .items-table .form td {
-  vertical-align: top;
+  vertical-align: middle;
 }
 .items-table td:not(:first-child),
 .grayed {
@@ -640,3 +652,42 @@ li::marker {
   min-width: 66%;
   width: max-content;
 }
+.measurements-section {
+  overflow-x: auto;
+}
+body[data-measurements-view=wide] .measurements-compact,
+body[data-measurements-view=compact] .measurements-wide {
+  display: none;
+}
+body[data-measurements-view=compact] .view-toggle[data-view=compact],
+body[data-measurements-view=wide] .view-toggle[data-view=wide] {
+  background-color: var(--color-blue);
+  border-color: var(--color-blue);
+  color: white;
+  fill: white;
+}
+#measurements tr.grouped td {
+  border-top: none;
+}
+#measurements tr.grouped .taken-at,
+#measurements tr.grouped .created-at {
+  visibility: hidden;
+}
+.measurements-wide td {
+  vertical-align: middle;
+  white-space: nowrap;
+}
+.wide-cell {
+  align-items: center;
+  display: inline-flex;
+  gap: 0.25em;
+}
+.wide-cell .button {
+  border: none;
+  font-size: inherit;
+  height: auto;
+  padding: 0;
+}
+.wide-cell button.link::after {
+  content: none;
+}