feat(workflow): data-reference chips (upstream-scoped, byte-safe)

[simlarsen]

The last and highest-risk piece of the workflow-builder simplification: turning the raw {{…}} data references into chips. Stacked on #2602 (GitHub retargets to master once the stack merges).

The problem

Referencing another step's output meant opening a full-screen modal that string-appended a raw token like {{local.components.slack-1.returnValues.error}} into the field — which you then had to read and manage by hand. No readability, no removal, no validation that the referenced step actually runs before this one.

What changed

For text arguments, the footer is now an inline data-reference helper:

• Existing tokens render as friendly, removable chips — Error · from Send to Slack — that turn red when the referenced step or output no longer exists.
• Insert from an inline menu scoped to upstream steps (with a "Show all steps" escape), so you can't reference data that won't exist at runtime.
• Variables still use the existing VariableModal.

Why this design (and not contentEditable)

The stored value stays a plain string — tokens are appended / index-spliced — so a workflow round-trips byte-for-byte and the executor is untouched. A rich contentEditable chip editor was deliberately avoided: it risks corrupting saved workflows and, critically, jsdom can't test it, so it couldn't be verified with the component-testing approach used here. Keeping the string as the source of truth makes all the logic pure and fully testable.

• Only text-like fields get the chip footer; JSON editors keep the existing modal picker.
• The set of fields that show a data-reference footer is unchanged — only the footer's UI changed.
• buildComponentToken / variable tokens are byte-identical to what ComponentValuePickerModal / VariableModal already produce.

Verification

• TokenUtils.test.ts (14): parse/classify/describe/append + byte-exact removeTokenOccurrence (correct occurrence among adjacent duplicates, surrounding text preserved, out-of-range no-op).
• DataReferenceInput.test.tsx (4, RTL/jsdom): chips render, broken-reference flagged, precise removal, upstream-scoped insert + show-all.
• 48 workflow tests pass; tsc ✓, eslint ✓.
• Adversarial review pass (dedicated agent) traced the full value-sync chain (setFieldValue → onChange → setComponent → props.fields → useAsyncEffect), confirmed the token formats byte-for-byte against the pickers and executor, and found no real bug or regression — only two theoretical nits that match pre-existing behavior.

🤖 Generated with Claude Code

[simlarsen]

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