feat: add demo entries with images + fix form upload action

- New demo entry: Arashiyama with single hero image (bamboo.jpg)
- New demo entry: Gyeongbokgung with four gallery images (palace-gate,
  throne-hall, hanok-rooftops, bugaksan)
- post-form.md: add upload: true to process block so filepond photo
  uploads are handled after page creation; simplify list-of-maps to
  flat map (Symfony YAML preserves insertion order)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/demo/tracker/2026-03-31-0730-last-morning-in-arashiyama.entry/entry.md

@@ -0,0 +1,23 @@
+---
+title: 'Last Morning in Arashiyama'
+date: '2026-03-31 07:30'
+template: entry
+published: true
+hero_image: 'bamboo.jpg'
+lat: '35.0094'
+lng: '135.6728'
+location_city: 'Kyoto'
+location_country: 'Japan'
+weather_temp_c: 13
+weather_desc: 'Partly cloudy'
+---
+
+The alarm went off at 6am and I almost ignored it. Then I remembered why I had set it: Arashiyama before the crowds arrive.
+
+By 7am the bamboo grove was quiet. Not silent — bamboo is never silent, the stalks creak and the leaves hiss against each other in any breeze at all — but quiet in the sense of no one else being there. An hour later there would be tour groups and selfie sticks and the particular difficulty of appreciating something beautiful while surrounded by people also trying to appreciate it. At 7am there was just the grove and the green light filtering down through the canopy and a single cat sitting very still on a stone wall watching me with professional indifference.
+
+I walked the main path twice. The stalks are taller than I expected, 15 or 20 metres, and they grow so densely that the sky mostly disappears. The colour is extraordinary: not one green but twenty, each stalk a slightly different shade depending on age and light, the whole thing shifting as the breeze moves through it.
+
+The Oi River was flat and grey in the morning light, a single cormorant fishing from a low rock. Across the water the hills were still wrapped in low cloud. I sat on a bench and ate a convenience store onigiri and watched the mist burn off slowly.
+
+Flight to Seoul at 2pm. Packing takes twenty minutes when you never properly unpack.

docs/demo/tracker/2026-04-02-1100-gyeongbokgung-and-beyond.entry/entry.md

@@ -0,0 +1,23 @@
+---
+title: 'Gyeongbokgung and Beyond'
+date: '2026-04-02 11:00'
+template: entry
+published: true
+hero_image: 'palace-gate.jpg'
+lat: '37.5796'
+lng: '126.9770'
+location_city: 'Seoul'
+location_country: 'South Korea'
+weather_temp_c: 12
+weather_desc: 'Sunny'
+---
+
+Sunday in Seoul and the whole city seemed to have the same idea: Gyeongbokgung Palace, the largest of the five grand palaces built during the Joseon dynasty, restored after the Japanese colonial period and now open and enormous and full of people doing what people do when confronted with a large photogenic space — walking through it slowly with their phones held in front of them.
+
+I did the same thing. The main gate, Gwanghwamun, is so large that the guards performing the changing ceremony looked like toys underneath it. The throne hall beyond has curved roofs that sweep upward at the corners in a way that seems to defy the weight of the tiles. Behind everything, Bugaksan mountain rises up, still snow-capped, framing the whole compound like a backdrop.
+
+I stayed for two hours then walked north to Bukchon Hanok Village: a hillside neighbourhood of traditional Korean houses, narrow lanes, and — given it was a Sunday — approximately four hundred other tourists also walking those narrow lanes. Worth it regardless. The geometry of the rooftops against the Seoul skyline is exactly as good as every photograph suggests.
+
+Afternoon: the National Folk Museum inside the palace grounds, a covered market near Insadong for dinner supplies, then back to Mapo on the subway reading a novel and failing to remember which stop was mine.
+
+Three days left in Korea. I am already sad about the food.

pages/02.post/post-form.md

@@ -94,10 +94,8 @@ form:
             classes: btn-post
 
     process:
-        -
+        add_page: true
-            add_page: true
+        upload: true
-        -
+        message: 'Entry posted successfully!'
-            message: 'Entry posted successfully!'
+        reset: true
-        -
-            reset: true
 ---