Consolidate gallery pages: gallery-1 becomes the main Galerie page

- Replace the old placeholder galerie page content with gallery-1's
  real content (text + 4 uploaded photos), keeping the /galerie route
  and its position in the main nav
- Remove gallery-2 and gallery-3 (prototype pages) and their media
- Switch section text fields from plain textarea to Grav's markdown
  editor type, restoring the formatting toolbar in Admin
- Trim the image grid/blueprint caps to 2 per section to match
  gallery-1's actual content

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

pages/03.galerie/galerie.en.md

@@ -1,15 +0,0 @@
----
-title: Gallery
-menu: Gallery
-intro: "An impression of Keramiekgalerie Groot Welsden – Natascha Rieter's studio and exhibition space in Bunde."
-section1_heading: 'Currently on display'
-section1_text: |
-    The gallery shows a changing selection of small sculptures, reliefs, clay paintings and monumental maquettes. *(editorial note: describe the current exhibition/setup here)*
-section1_images: []
-section2_heading: 'Visiting & purchasing'
-section2_text: |
-    The gallery is open every Friday and Saturday from 1pm to 5pm, and always by appointment. Works are for sale; ask about pricing and options during your visit or get in touch. Commissions and custom work are also possible.
-
-    For individual pieces, see the [Work in detail](/werk-in-detail) page.
-section2_images: []
----