feat: refine UI, improve UX, optimize the analysis pipeline, and add character standing positions

lib/prompts/novel-promotion/location_create.en.txt

@@ -7,13 +7,23 @@ User request:
 Rules:
 1. Output in English only.
 2. Start with scene name in this format: "[Scene Name] ..."
-3. Describe a wide, clear environment with spatial layout and key objects.
-4. Mention lighting direction and atmosphere.
-5. No protagonist actions or dialogue.
-6. If crowd is implied by context, use generic crowd terms only (guests, pedestrians, audience).
+3. Describe a wide, complete environment with controllable spatial layout, key structures, and visible depth.
+4. Make foreground, midground, and background explicit.
+5. Define at least 3 clear anchor objects or anchor areas and make the nearby open space visible.
+6. If the user input is generic, such as 「classroom」 or 「office」, proactively make it specific enough for stable image layout instead of staying generic.
+7. Mention lighting direction and atmosphere.
+8. No protagonist actions or dialogue.
+9. If crowd is implied by context, use generic crowd terms only (guests, pedestrians, audience).
+10. Also generate 2-6 fixed `available_slots` as complete descriptive placement phrases tied to concrete scene anchors.
+11. Do not mention posture, action, or emotion in `available_slots`. Describe position only.
+12. Every anchor mentioned in `available_slots` must appear clearly in the scene prompt.
 
 Output format:
 Return JSON only. ⚠️ JSON SAFETY: All quotation marks MUST be converted to corner brackets「」in JSON string values:
 {
-  "prompt": "[Scene Name] environment description"
+  "prompt": "[Scene Name] environment description",
+  "available_slots": [
+    "the position beside the left edge of the dining table",
+    "the open space just inside the doorway against the wall"
+  ]
 }