--track: Bahnzusammenhang aus der TrackIds-Spalte statt aus Nachbarn

build_track_graph baut die Fein-Adjazenz jetzt direkt aus der geordneten
TrackIds-Spalte je Container (Element.track_ids): Kreisel als zirkulaerer
Umlauf in Drehrichtung (Export-Sortierung), Strecke/Gefaelle als lineare
Kette AS -> SEP.. -> ES. Gemeinsame AS/ES-/Weiche-Knoten verketten die
Container automatisch - die Rueckmeldungs-/Rollen-Heuristik aus der
Nachbarn-Spalte (_transfer_kreisel_lane, _wire_weiche,
_orient_separator_links) entfaellt komplett.

_attach_track_symbols misst offene Bahnenden jetzt am feinen Graphen statt
am groben; das behebt die vereinzelten Falsch-Eingaenge an voll verketteten
Bahnen (HundM05: Bahn 0001-0004, 0006-R).

Doku in doc/Python_Scripts.md und doc/track.md nachgezogen.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

doc/Python_Scripts.md

@@ -153,23 +153,35 @@ bidirectional and reported as a warning. `--doc` additionally cross-checks
 stated `Anzahl_Separator`/`Anzahl_Scanner` counts against what was actually
 attached.
 
-`--track` builds a second, finer-grained graph instead of (in addition to) the
-one above: Separator, Ausschleus-/Einschleuselement and Weiche each become
-their own node (they supply no node in the graph described above), showing
-the actual branch/merge/crossing topology between Kreisel rather than just the
-mechanical objects. See `doc/track.md` for the derivation rules and its
-tested-against-`mubea_export.csv` findings; short version:
+`--track` builds a second, finer-grained graph in addition to the one above:
+Separator, Ausschleus-/Einschleuselement, Weiche and the entry/exit points
+(BTMT Be-/Entladung, Eingang/Ausgang) each become their own node (they supply
+no node in the graph described above), showing the actual branch/merge/crossing
+topology between Kreisel rather than just the mechanical objects.
 
-- **Ausschleuselement** → 1 incoming (Kreisel-side) → 2 outgoing (continues
-  on the Kreisel-Bahn *and* branches onto the Strecke) — a fork.
-- **Einschleuselement** → 2 incoming (from the Strecke *and* continuing on
-  the Kreisel-Bahn) → 1 outgoing — a merge.
-- **Weiche** → 4-way crossing between two Kreisel (in/out on each side, from
-  `Drehrichtung` via the existing `_weiche_lane_roles`).
-- A Kreisel-Bahn with no separator resolvable to a specific position (or with
-  several that aren't chained to each other in the export) is drawn as a
-  dashed **placeholder** node rather than guessed — the intended hand-off
-  point for a later geometry-based ordering pass (not implemented yet).
+The ordering comes **directly from the `TrackIds` CSV column** (`Element.track_ids`):
+every container — Kreisel, Strecke, Gefällestrecke — carries the ordered list of
+the track elements lying on it, computed by the dxfmakros export
+(`dxfmakros/doc/csv-export.md`). `build_track_graph` draws one directed chain per
+container from that list:
+
+- **Kreisel** → the circular umlauf in `Drehrichtung` order (the list is already
+  angle-sorted); consecutive entries are linked and the last closes back onto the
+  first (a real, closed loop). Edges are drawn light-blue ("Umlauf").
+- **Strecke / Gefällestrecke** → the linear chain `AS → SEP… → ES` in build
+  order, oriented by its ends (Ausschleuselement = start, Einschleuselement =
+  end). Edges are drawn blue ("Bahn").
+- An element listed in **two** containers (an AS/ES sits in its Strecke *and* in
+  the docked Kreisel's umlauf; a Kreisel-Kreisel Weiche sits in both Kreisel) is
+  the **same node** and stitches the containers together automatically — no
+  `Nachbarn`-based role/feedback heuristic any more.
+- A track element that appears in **no** `TrackIds` list (e.g. a free Separator
+  the export didn't chain) is hung off a dashed **placeholder** for its
+  `Zuordnung` with an "unbestimmt" edge and a warning — order on that Bahn left
+  open. If the CSV has no `TrackIds` column at all (older export), every track
+  element falls into this case.
+
+See `doc/track.md` for the fuller derivation notes.
 
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