feat: add non-empty-string type annotation for pattern

- FabricPromptInterface::getPattern() now returns non-empty-string
- FabricPrompt constructor expects non-empty-string for pattern
- Improves type safety and PHPStan analysis

Author: OskarStark

src/Platform/Fabric/FabricPrompt.php

@@ -10,6 +10,7 @@
 final readonly class FabricPrompt implements FabricPromptInterface
 {
     /**
+     * @param non-empty-string $pattern
      * @param array<string, mixed> $metadata
      */
     public function __construct(
@@ -19,6 +20,9 @@ public function __construct(
     ) {
     }
 
+    /**
+     * @return non-empty-string
+     */
     public function getPattern(): string
     {
         return $this->pattern;

src/Platform/Fabric/FabricPromptInterface.php

@@ -11,6 +11,8 @@ interface FabricPromptInterface
 {
     /**
      * Get the pattern name (e.g., 'create_summary').
+     *
+     * @return non-empty-string
      */
     public function getPattern(): string;