feat(undo-redo): unify field, code, and loop config edits into one stack by waleedlatif1 · Pull Request #4875 · simstudioai/sim

- Record block-level field edits (tools, model, prompts, dropdowns, sliders,
  tag/reference insertion) on the workflow undo stack
- Consolidate the separate per-field code-editor stack into the workflow stack
  and delete it; route Cmd+Z/redo in every text editor to the workflow undo so
  native/editor undo is suppressed and there is one source of truth
- Make loop/parallel config values (iterations, collection, condition, batch
  size) undoable; coalesce consecutive same-field edits into one step
- Group the model->apiKey clear into a single undo step
- Reveal the affected block (select + open its editor panel) on undo/redo so a
  reverted field change is never off-screen

Code-field undo frames are large and accumulate quickly; keeping them in the
synchronous localStorage-backed stack risked main-thread jank on every keystroke
and the ~5MB quota. Move the unified undo store to async IndexedDB (idb-keyval),
matching how the old separate code stack was persisted.

- Replace the localStorage persist adapter with a throttled IndexedDB adapter
  (coalesces a burst of writes into one transaction; flushes on tab hide)
- Delete the now-orphaned code-storage adapter

- collaborativeBatchSetSubblockValues: capture each field's real prior value
  before mutating instead of recording before: update.expectedValue, which was
  undefined when a caller omitted expectedValue (would undo a field to undefined)
- List the stable recordSubflowFieldUpdate helper in the subflow methods'
  dependency arrays
- Document that a multi-block batch undo reveals only its first block