feat: home page template with carousel, news, about, services, team sections

- Extends base.html, uses shared image macro for resize_image
- Refactored img shortcode to forward to macros/image.html (DRY)
- News pulled via get_page from content/news.md
- Notfall section skipped (was unpublished in grav)
- Map call commented out until shortcode lands in Task 20

templates/macros/image.html

@@ -0,0 +1,15 @@
+{# Image-rendering macro, used both by templates (directly via import)
+   and indirectly by the `img` shortcode (which forwards to it). #}
+
+{% macro render(src, width, alt="", class="") %}
+  {%- set source_path = "static/images/" ~ src -%}
+  {%- set resized = resize_image(path=source_path, width=width, op="fit_width", quality=85) -%}
+  <img
+    src="{{ resized.url }}"
+    width="{{ resized.width }}"
+    height="{{ resized.height }}"
+    alt="{{ alt }}"
+    {%- if class %} class="{{ class }}"{% endif %}
+    loading="lazy"
+  >
+{% endmacro render %}