[Workflows] Allow iterator to take whole item as variable (#22031)

**Select the whole item in iterator loops, and iterate over a step's
array output**
## Summary
Two related improvements to working with lists in workflows:
- Pick the current item as a whole inside an iterator loop. Previously,
in a node inside the loop, you could only reference individual fields of
the Iterator's current item. Now you can select the whole item (e.g. a
full record) — useful for passing it straight into a downstream step.
<img width="1270" height="744" alt="Screenshot 2026-06-23 at 17 02 47"
src="https://github.com/user-attachments/assets/6b92e72e-ec25-4c1a-9841-3a438210e753"
/>
- Iterate over a step's array output. A Code / Logic Function step that
returns a top-level array couldn't be fed to the Iterator: its output
was flattened into indexed entries (0, 1, …) with no way to select the
array as a whole. A new "Whole list" option selects the step's entire
output, and the Iterator infers the per-iteration item shape from it.
<img width="1026" height="728" alt="Screenshot 2026-06-23 at 17 17 53"
src="https://github.com/user-attachments/assets/db07dcd8-4fb8-4db9-8b45-aa56051d9f3b"
/>


Together these complete the loop ergonomics: select a list → iterate →
reference the current item (whole or by field) downstream — matching the
model used by tools like Windmill.

## What changed
- The variable picker offers a "Use the whole item" option when viewing
an iterator's current item, and a "Whole list" option when a step
returns a top-level array.
- The Iterator's current-item schema can now be inferred from a variable
pointing at a step's whole output.

## Risks for existing workflows
None expected. The change is purely additive:
- No DB migration and no change to how output schemas are stored or read
— existing schemas, variables, and iterators behave identically.
- No change to runtime variable resolution; existing {{step.field}} and
current-item references are untouched.
- The new options only apply to new selections (whole item / whole
list); all existing paths take the unchanged code path.
- The only edge case: array detection is heuristic (an output whose keys
are exactly 0…n-1), so an object that happens to have those keys would
also show "Whole list". This is rare for real outputs, affects nothing
unless a user selects it, and fails safe — the Iterator validates its
input and throws a clear "items must be an array" error if a non-array
is passed.

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---------

Co-authored-by: Charles Bochet <charles@twenty.com>

packages/twenty-server/src/modules/workflow/workflow-builder/workflow-schema/workflow-schema.workspace-service.ts

@@ -11,8 +11,10 @@ import {
   buildManualTriggerMetadataNode,
   BulkRecordsAvailability,
   extractRawVariableNamePart,
+  getCurrentItemSchemaFromFlattenedArrayOutputSchema,
   GlobalAvailability,
   isBaseOutputSchemaV2,
+  isFlattenedArrayOutputSchema,
   navigateOutputSchemaProperty,
   SingleRecordAvailability,
   TRIGGER_STEP_ID,
@@ -653,8 +655,26 @@ export class WorkflowSchemaWorkspaceService {
       case WorkflowActionType.HTTP_REQUEST:
       case WorkflowActionType.LOGIC_FUNCTION: {
         const propertyPath = extractPropertyPathFromVariable(items);
+        const outputSchema = this.getOutputSchemaWithExpectedFallback(
+          step.settings,
+        );
+
+        const variableTargetsWholeStepOutput = propertyPath.length === 0;
+
+        if (variableTargetsWholeStepOutput) {
+          if (!isFlattenedArrayOutputSchema(outputSchema)) {
+            return DEFAULT_ITERATOR_CURRENT_ITEM;
+          }
+
+          return (
+            getCurrentItemSchemaFromFlattenedArrayOutputSchema({
+              schema: outputSchema,
+            }) ?? DEFAULT_ITERATOR_CURRENT_ITEM
+          );
+        }
+
         const schemaNode = navigateOutputSchemaProperty({
-          schema: this.getOutputSchemaWithExpectedFallback(step.settings),
+          schema: outputSchema,
           propertyPath,
         });