feat(workflow): exclude text-capable nodes with connected text from send targets

CLIP Text Encode and friends whose text widget is backed by a connected
input cannot have their text changed via the widget (execution reads the
linked input), so sending to them was a silent no-op.

- Registry: compute text_widget_connected capability from the widget's
  backing input link state; has_text_widget drops to false when wired;
  include the flag in the registration fingerprint so link changes
  re-register the affected nodes
- Registry: hook link connect/disconnect (graph events on new litegraph,
  onAfterChange fallback for classic) on root and subgraphs, plus
  subgraph-created for future subgraphs
- applyWidgetUpdate: skip inject_text when the target widget is connected
  and self-heal the registry instead of writing a value that is ignored
- Web UI: drop text_widget_connected nodes from prompt/embedding send
  candidates; show a Mark as -> Send Prompt Target hint toast when no
  candidates remain (new uiHelpers.workflow.noPromptTargets key, synced
  to all locales; zh-CN/zh-TW translated)
- Extract shared resolveTextWidget() used by both the candidate-set
  logic and the write path so the two cannot drift apart
- Tests: workflow registry connection-state registration, subgraph
  handling, fingerprint re-registration, inject_text write/skip paths,
  setup link-change hooks; uiHelpers candidate filtering and hint toast

locales/de.json

@@ -1726,6 +1726,7 @@
             "recipeReplaced": "Rezept im Workflow ersetzt",
             "recipeFailedToSend": "Fehler beim Senden des Rezepts an den Workflow",
             "noMatchingNodes": "Keine kompatiblen Knoten im aktuellen Workflow verfügbar",
+            "noPromptTargets": "[TODO: Translate] No compatible prompt targets in the workflow.\nRight-click a node in ComfyUI → Mark as → Send Prompt Target",
             "noTargetNodeSelected": "Kein Zielknoten ausgewählt",
             "modelUpdated": "Modell im Workflow aktualisiert",
             "modelFailed": "Fehler beim Aktualisieren des Modellknotens",