fix(workflow): optimize loop/parallel regeneration and prevent duplicate agent tools (#3100)

* fix(workflow): optimize loop/parallel regeneration and prevent duplicate agent tools

* refactor(workflow): remove addBlock in favor of batchAddBlocks

- Migrated undo-redo to use batchAddBlocks instead of addBlock loop
- Removed addBlock method from workflow store (now unused)
- Updated tests to use helper function wrapping batchAddBlocks
- This fixes the cursor bot comments about inconsistent parent checking

Author: waleedlatif1