windows: fix pynsist installer.cfg to generate launcher; add EntryPoints gui_scripts, correct Include syntax; keep icon=icons/app.ico; remove invalid Shortcut section

Author: Ananyin

installer.cfg

@@ -1,7 +1,6 @@
 [Application]
 name=FilantropiaSolar
 version=1.2.1
-entry_point=main:main
 icon=icons/app.ico
 publisher=FilantropiaSolar
 
@@ -11,13 +10,22 @@ bitness=64
 include_msvcrt=true
 
 [Include]
-files=Data;weather_files;average_values.csv
+packages =
+    filantropia_solar
+py_modules =
+    main
+files =
+    Data
+    weather_files
+    average_values.csv
+
+[EntryPoints]
+# Creates FilantropiaSolar.exe GUI launcher and Start Menu shortcut
+# Keep the name without spaces for a clean executable name
+# Maps to main:main (main.py in project root)
+gui_scripts =
+    FilantropiaSolar = main:main
 
 [Build]
 directory=build/nsist
 installer_name=FilantropiaSolar-1.2.1.exe
-
-[Shortcut]
-shortcut_name=FilantropiaSolar
-desktop_shortcut=true
-start_menu_shortcut=true