feat: ID-Vorschläge beim Tippen von Abhängigkeiten (:#) — D63

Wer :# tippt, bekommt die vergebenen IDs als Liste an der Schreibmarke:
Präfix- vor Teilstring-Treffern, Knotentitel als Kontext, schon gelistete
und die eigene ID ausgenommen. ↑/↓ wählt, Enter/Tab übernimmt (undo-fähig),
Esc schließt; Live-Region für Screenreader. Eingabehilfe wie die Kurzform
(D55) — der Parser sieht nie etwas davon. Regeln headless in autocomplete.js
(20 Tests), app.js verdrahtet Popup, Tasten und Einfügen.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/examples/werkbaum.werkbaum

@@ -72,6 +72,7 @@
     - [^] #ed.jump: Jump between diagram and text (S)
     - [^] #ed.lineno: Line numbers in the text editor (XS)  %% the warnings name them
     - [^] #ed.shortid: Type #.kc under #prod-stage, get #prod-stage.kc (XS)  %% an input aid, not notation
+    - [x] #ed.depcomplete: Typing :# suggests the known ids (S)  %% arrows choose, Enter inserts
     - [^] #ed.showids: A # button shows the ids before the titles (XS)  %% written as in the text, with a colon
       - [^] #ed.lineno.tip: The warning is the tooltip of its number (XS)  %% no hunting in the list
     - [^] #ed.fold: Collapsible subtrees (L)
@@ -526,6 +527,11 @@
   typing, not while parsing: the file keeps the full id, so it stays greppable
   and survives re-ordering, which is what the :#... references rely on.
 
+#ed.depcomplete
+  A dependency needs its target's id, and nobody remembers 180 of them. The
+  list at the caret offers the document's ids filtered by what is typed, with
+  the node title as context; an input aid like the shorthand, not notation.
+
 #ed.showids
   The id is the address of a node, but the diagram only carried it in the
   tooltip. The switch writes it before the title the same way the text does,