refactor: remove dead code and obsolete examples (#76)

- Remove ToolChain, ResourceChain, PromptChain classes
- Remove Collection/Identifier/Metadata interfaces (only used by old Chains)
- Remove ToolCollectionInterface (unused)
- Delete obsolete examples 09-standalone-cli and 10-simple-http-transport
- Fix STDERR handling in bootstrap.php for web environments
- Clean up CHANGELOG.md

examples/bootstrap.php

@@ -44,9 +44,9 @@ function logger(): LoggerInterface
 
             if ($_SERVER['FILE_LOG'] ?? false) {
                 file_put_contents('dev.log', $logMessage, \FILE_APPEND);
+            } elseif (defined('STDERR')) {
+                fwrite(\STDERR, $logMessage);
             }
-
-            fwrite(\STDERR, $logMessage);
         }
     };
 }