Add callouts to LocallyGrown series for enhanced readability

Applied strategic callouts across all 4 posts in the LocallyGrown series:
- Info, success, warning, danger, tip, quote, and example callouts
- Improved visual hierarchy and information highlighting
- Better mobile readability with structured content blocks

🤖 Generated with [Claude Code](https://claude.ai/code)

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

layouts/shortcodes/callout.html

@@ -0,0 +1,37 @@
+{{- $type := .Get "type" | default "note" -}}
+{{- $title := .Get "title" | default (title $type) -}}
+{{- $icon := "" -}}
+
+{{- if eq $type "note" -}}
+  {{- $icon = "📝" -}}
+{{- else if eq $type "tip" -}}
+  {{- $icon = "💡" -}}
+{{- else if eq $type "info" -}}
+  {{- $icon = "ℹ️" -}}
+{{- else if eq $type "warning" -}}
+  {{- $icon = "⚠️" -}}
+{{- else if eq $type "danger" -}}
+  {{- $icon = "🚨" -}}
+{{- else if eq $type "success" -}}
+  {{- $icon = "✅" -}}
+{{- else if eq $type "question" -}}
+  {{- $icon = "❓" -}}
+{{- else if eq $type "quote" -}}
+  {{- $icon = "💬" -}}
+{{- else if eq $type "example" -}}
+  {{- $icon = "📋" -}}
+{{- else if eq $type "bug" -}}
+  {{- $icon = "🐛" -}}
+{{- else -}}
+  {{- $icon = "📌" -}}
+{{- end -}}
+
+<div class="callout callout-{{ $type }}">
+  <div class="callout-title">
+    <span class="callout-icon">{{ $icon }}</span>
+    <span>{{ $title }}</span>
+  </div>
+  <div class="callout-content">
+    {{ .Inner | markdownify }}
+  </div>
+</div>