feat(workflow) - Add validation layer (#21422)

Add workflow validation framework and consolidate output schema
types/search logic into twenty-shared

This PR introduces a comprehensive workflow validation system that
catches configuration errors at build-time, and consolidates the
fragmented output-schema type definitions and variable-search logic from
the front-end into twenty-shared

**Workflow validation** — A new system that checks workflows for errors
before activation: graph connectivity (unreachable steps, dangling
references), step parameter schemas (via Zod), variable references
(typos, wrong step order), and workspace metadata (non-existent
objects). Returns structured errors/warnings with "did you mean?"
suggestions. Runs automatically after create_complete_workflow and
update_workflow_version_step, and is also available as a standalone
validate_workflow tool.

**Output schema consolidation** — Moves all output schema types and the
variable-search logic from scattered front-end files into twenty-shared,
replacing ~800 lines of duplicated per-schema-type code with a single
unified searchVariableInOutputSchema dispatcher.


To do : 
- validation on CODE and AGENT step

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

packages/twenty-server/src/engine/workspace-manager/twenty-standard-application/utils/skill-metadata/create-standard-flat-skill-metadata.util.ts

@@ -74,6 +74,11 @@ Always rely on tool schema definitions:
 - Follow schema definitions exactly for field names, types, and structures
 - Schema includes validation rules and common patterns
 
+## Validation
+
+The \`create_complete_workflow\` and \`update_workflow_version_step\` tools automatically run validation after their operation and include the results in the response. Review any reported errors and fix them before activating the workflow.
+
+
 ## Approach
 
 - Ask clarifying questions to understand user needs