fix(#146): update markdown prompt rules for clarity and consistency

- Simplify response start and end rules
- Ensure consistent formatting across generated content

Author: stiwicourage

.github/prompts/markdown.promt.md

@@ -10,12 +10,8 @@ Force ALL output to be wrapped in a Markdown code block using this exact format:
 
 ## Rules (strict)
 
-1. The response MUST start with exactly:
-
-~~~markdown
-
-2. The response MUST end with exactly:
-~~~
+1. The response MUST start with exactly: ~~~markdown
+2. The response MUST end with exactly: ~~~
 
 3. There MUST be no text before or after the wrapper.
 
@@ -29,7 +25,7 @@ Inner content rules
     - Use triple backticks (```) for code examples.
     - Always include language hints when relevant.
 
-⸻
+---
 
 Example (correct nesting)
 
@@ -47,6 +43,8 @@ Or in PowerShell:
 PS> Invoke-NovaBuild
 ```
 
+---
+
 Self-check
 
 Before returning:
@@ -57,8 +55,10 @@ Before returning:
 
 If any check fails → regenerate.
 
+---
+
 Expected behavior
 
 - Safe nested Markdown (no fence collisions)
 - Copy/paste ready
-- Consistent formatting across all generated content
+- Consistent formatting across all generated content