fix(encoding): fix last corrupted sequence on L1441 (ΓÇö → —)

Replace Windows CP437 terminal artefact 'ΓÇö' with em dash —.
Root cause: em dash (U+2014, UTF-8 E2 80 94) copy-pasted from a Windows
terminal in OEM codepage, producing a multi-step encoding corruption
not catchable by the Win1252 reverse-map algorithm.

Author: bertheto

src/static/index.html

@@ -1438,7 +1438,7 @@
     // Extras: thread state & close (REST shims)
     // ==============================================================================================
     // Extend the REST API with two extra POST endpoints that main.py may serve later.
-    // If they 404, we silently ignore ΓÇö the MCP tool path is the canonical way.
+    // If they 404, we silently ignore — the MCP tool path is the canonical way.
 
     // ==============================================================================================
     // Utilities