Add wizard UI, general-assembly resolution, and test suite

Restructure Form1 into a sequential wizard (database -> import -> raw ->
recursive component resolution -> completeness/STEP report), fix
case-sensitivity bugs in codice/tipo_file lookups and a word-boundary gap
in the assembly scanner that missed _D100-style sub-assembly references,
and treat the distinta's general assembly as an ordinary CSV row (derived
from the DBP_<codice>_<timestamp> filename) instead of special-casing it
throughout. Also adds CadSearchGui.Tests (xUnit) covering the scanner,
filename parsing, and the case-insensitive DB lookup behavior.

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

.gitignore

@@ -29,3 +29,7 @@ publish/
 /raw/
 /step/
 *.dxc
+
+# Report BOM generati manualmente da Creo per debug/validazione: mai una dipendenza
+# della pipeline (che deve funzionare senza Creo), solo un aiuto occasionale.
+*.bom.*