fix: address code review issues from alpha.14 to alpha.15 (#1068)

* fix: remove debug console.log statements from ui.js

* fix: add error handling and rollback for temp directory cleanup

* fix: use streaming for hash calculation to reduce memory usage

* refactor: hoist CustomHandler require to top of installer.js and ui.js

* fix: fail fast on malformed custom module YAML

User customizations must be valid - silent skip hides broken configs.

* refactor: use consistent return type in handleMissingCustomSources

* refactor: clone config at install() entry to prevent mutation

tools/cli/installers/lib/modules/manager.js

@@ -391,8 +391,8 @@ class ModuleManager {
           if (config.code === moduleName) {
             return modulePath;
           }
-        } catch {
-          // Skip if can't read config
+        } catch (error) {
+          throw new Error(`Failed to parse module.yaml at ${configPath}: ${error.message}`);
         }
       }
     }