Add neighbour planting sidebar with improved styling and layout

app/assets/stylesheets/_plantings.scss

@@ -694,7 +694,55 @@
     margin-left: 0.5rem;
   }
 
-  .neighbours .index-cards .card {
-    width: 100%;
+  // Neighbours are a list, not a grid: in a narrow column a full planting card
+  // is one huge photo each. A small photo, who grows it and where is enough to
+  // decide whether to go and look.
+  .planting-neighbours-lead {
+    margin-bottom: 0.75rem;
+  }
+
+  .planting-neighbours {
+    display: flex;
+    flex-direction: column;
+  }
+
+  .planting-neighbour {
+    display: flex;
+    align-items: center;
+    gap: 0.6rem;
+    padding: 0.5rem 0;
+    border-top: 1px solid rgba(65, 63, 59, 0.12);
+    color: inherit;
+    text-decoration: none;
+
+    &:first-child {
+      border-top: 0;
+    }
+
+    &:hover,
+    &:focus {
+      background: rgba(65, 63, 59, 0.04);
+    }
+  }
+
+  .planting-neighbour-photo {
+    flex: 0 0 auto;
+    width: 48px;
+    height: 48px;
+    border-radius: $card-radius;
+    object-fit: cover;
+  }
+
+  .planting-neighbour-text {
+    min-width: 0;
+    font-size: 0.9rem;
+    line-height: 1.3;
+  }
+
+  .planting-neighbour-where {
+    display: block;
+    color: rgba(65, 63, 59, 0.7);
+    font-size: 0.8rem;
+    overflow-wrap: anywhere;
   }
 }

app/views/plantings/_neighbour.html.haml

@@ -0,0 +1,14 @@
+-# One neighbouring planting, as a compact sidebar row. Not plantings/_card:
+-# that is a card for a grid, and in a narrow column it is one huge photo per
+-# neighbour, with the owner's quick-actions menu floating over it.
+= link_to planting_path(neighbour), class: 'planting-neighbour' do
+  = image_tag neighbour.thumbnail_url || placeholder_image, alt: '', class: 'planting-neighbour-photo'
+  %span.planting-neighbour-text
+    %strong= neighbour.owner_login_name
+    %span.planting-neighbour-where
+      -# The crop is the same for every neighbour, so the useful facts are who
+      -# grows it and where.
+      = neighbour.garden_name
+      - if neighbour.location.present?
+        ·
+        = neighbour.location

app/views/plantings/show.html.haml

@@ -112,7 +112,8 @@
         %section.neighbours
           .section-header
             %h2= t('plantings.show.neighbours')
-          .index-cards
+          %p.text-muted.small.planting-neighbours-lead
+            = t('plantings.show.neighbours_explanation', crop: @planting.crop.name)
+          .planting-neighbours
             - @neighbours.each do |neighbour|
-              = render 'plantings/card', planting: neighbour
-          %p.text-muted= t('plantings.show.neighbours_explanation', crop: @planting.crop.name)
+              = render 'plantings/neighbour', neighbour: neighbour