fix(understand): the bare Russian "to" before a panel is a wiring callout

A Russian P&ID often closes a load's text with the panel it is wired to:
'... кВт' on one line, then 'к CP1' ('to CP1') or 'к щиту CP-2' ('to
switchboard CP-2') on the next. wiring_target knew 'подключение к ...' but
not the bare preposition. On the field P&ID most loads therefore had no
panel and no measurable cable.

The preposition к / ко now counts when it is a whole word and the panel is
the next word, optionally after щиту / шкафу / панели. The к of кВт is
never read as the preposition. The new test failed before the change.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FKFStjEFzpGyLq5bMpWxTd

README.md

@@ -27,7 +27,7 @@ Live through COM on Windows, or headless through ezdxf anywhere — one typed co
 
 </div>
 
-> **v1.5 release snapshot:** 247 tools · 8 resources · 5 prompt templates · 4981 collected tests.
+> **v1.5 release snapshot:** 247 tools · 8 resources · 5 prompt templates · 4982 collected tests.
 > 247 is the **registered** count; a default install advertises 242 over `tools/list`,
 > because `ENABLE_3D` is unset. `system_about` is the runtime authority.