fix: widen all catch blocks from \Exception to \Throwable

PHP 8.3 TypeError and Error extend \Throwable but NOT \Exception,
so catch(\Exception) silently drops them — explaining why the
generation pipeline fails at the publishing step with no activity
log entry. Now every catch in the generation path catches
\Throwable and logs the exception class name for diagnostics.

Bump to v0.2.7.

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

includes/core/class-image-prompt-builder.php

@@ -173,10 +173,10 @@ PROMPT;
 			if ( '' !== $scene ) {
 				return $scene;
 			}
-		} catch ( \Exception $e ) {
+		} catch ( \Throwable $e ) {
 			// LLM failure is not fatal — fall back to rule-based synthesis.
 			PRAutoBlogger_Logger::instance()->warning(
-				'Image prompt LLM rewrite failed, using fallback: ' . $e->getMessage(),
+				sprintf( 'Image prompt LLM rewrite %s, using fallback: %s', get_class( $e ), $e->getMessage() ),
 				'image_prompt_builder'
 			);
 		}