Add TRO annotation tool writing an annotated copy of the drawing

Takes the original DXF, the CSV export and the derived TROs and writes a copy of
the drawing with the TRO information overlaid. The original is never touched.

Per TRO a block marker with attributes, not loose geometry: one block definition
per type (TRO_SYM_<type>), inserted at the plant coordinate, carrying TRO_ID,
TRO_TYPE, FB_BLOCK visibly and ITEMS, CONFIDENCE, SEPARATORS as hidden data.
That makes the result queryable and editable inside BricsCAD, and a corrected
TRO_ID can later feed back into the generator.

Layers follow the colour groups of tro_catalog (TRO_MARKER_sep, _vario, _store,
...) with the group colour as true colour and entities BYLAYER, so the layer
manager filters by TRO type. Flow arrows and the legend get their own layers.

Re-runs are idempotent through XDATA, not layer names: every generated entity is
tagged with the SPS_SKEL_TRO appid and a re-run deletes exactly those. Deleting
by layer would also destroy anything a user had put on the same layer.

Switches follow the other tools; --check reports the registration and what would
be drawn without writing, --flow adds the TRO-level arrows, --fb shows the
function block, --offset and --re-register override the stored transform. DWG is
rejected with a clear message since ezdxf cannot read it.

Verified against the real 23.8 MB drawing: 9 markers on the correct layers with
readable attributes, 15 flow arrows, and a re-run replaces its own 46 entities
instead of duplicating them.

Adds ezdxf to requirements and stores the verified Mubea transform in cfg/.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

requirements.txt

@@ -3,5 +3,11 @@
 
 pydantic >= 2.0.0
 
+# DXF lesen und schreiben (tro_annotate). DWG wird nicht unterstuetzt.
+ezdxf >= 1.4.0
+
+# Nur fuer Vorschaubilder eines DXF (ezdxf.addons.drawing) - optional:
+# matplotlib >= 3.8
+
 # Noch nicht benoetigt:
 # pytest >= 9.0.0