refactor: reorganize project structure for clarity

Move documentation assets to .github/assets/ and backend scripts to pacman-server/scripts/. Updates all references in README and Justfile.

Justfile

@@ -52,7 +52,7 @@ push:
 
 # Create a postgres container for the server
 server-postgres:
-	bun run .scripts/postgres.ts
+	bun run pacman-server/scripts/postgres.ts
 
 # Build the server image
 server-image:

README.md

@@ -2,7 +2,7 @@
 <!-- markdownlint-disable MD041 -->
 
 <div align="center">
-  <img src="assets/banner.png" alt="Pac-Man Banner Screenshot">
+  <img src=".github/assets/banner.png" alt="Pac-Man Banner Screenshot">
 </div>
 
 # Pac-Man
@@ -49,16 +49,16 @@ However, every commit has build artifacts, so you can grab the [latest build art
 ## Screenshots
 
 <div align="center">
-  <img src="assets/screenshots/0.png" alt="Screenshot 0 - Starting Game">
+  <img src=".github/assets/screenshots/0.png" alt="Screenshot 0 - Starting Game">
   <p><em>Starting a new game</em></p>
 
-  <img src="assets/screenshots/1.png" alt="Screenshot 1 - Eating Dots">
+  <img src=".github/assets/screenshots/1.png" alt="Screenshot 1 - Eating Dots">
   <p><em>Pac-Man collecting dots and avoiding ghosts</em></p>
 
-  <img src="assets/screenshots/2.png" alt="Screenshot 2 - Game Over">
+  <img src=".github/assets/screenshots/2.png" alt="Screenshot 2 - Game Over">
   <p><em>Game over screen after losing all lives</em></p>
 
-  <img src="assets/screenshots/3.png" alt="Screenshot 3 - Debug Mode">
+  <img src=".github/assets/screenshots/3.png" alt="Screenshot 3 - Debug Mode">
   <p><em>Debug mode showing hitboxes, node graph, and performance details.</em></p>
 </div>