feat: dynamic form fields, JSON output, branched questionnaires

CHANGELOG.md

@@ -6,6 +6,23 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 ### Added
+- Branched questionnaires: `[visible_if feld=Wert]` markers in a
+  `CustomInputForm` field's `info` (code editor) show the field only when
+  the condition holds — nested to any depth, with `&` for AND conditions
+  and quotes for values with spaces. The parser emits `allOf`/`if`/`then`
+  branches (branch-scoped `required`, template-order placement); unknown
+  triggers, cycles, and unsupported trigger types fail open (always
+  visible). New demo flow `bauvorhaben.json` (4 levels + sibling branch +
+  bool trigger). Values of hidden fields are kept and submitted.
+### Changed
+- `CustomInputForm.collect()` is now dynamic and returns `Data` (JSON)
+  instead of `Message`: fields can be renamed, added, or removed in the
+  Langflow code editor with no `collect()` change, and values travel as a
+  real JSON object. The form parser keeps `name` keys verbatim (empty
+  names skipped, collisions suffixed) and the run envelope merges unknown
+  keys. Note: a terminal `ChatOutput` renders `Data` as a fenced ```json
+  block, and downstream components should read `.data`, not `.text`.
+### Added
 - Flow-Sync ist jetzt ein manueller Full-Pass: `POST /api/flows/sync`
   (Button "Aus Langflow synchronisieren" in der Verwaltung) holt erst alle
   Flows aus Langflow nach `backend/flows/*.json` und deployed sie danach