ide: the Atmel Studio solution master has, on the libavr port

master opens in Studio, so this branch should too. One project, the port's own
chip, flags mirrored by hand against the CMake build — and the acceptance is
not that it builds but that it builds the same firmware: .text (7094 B) and
.data (336 B) come out byte-identical to the CMake output from the same
sources.

libavr is found through $(LIBAVR_ROOT), the variable the CMake build already
uses, so no machine path is committed; Studio expands it from the environment.
The toolchain is named by flavour only, since nothing Studio ships can compile
-std=c++26 and the path to one that can is per-machine state.

The componentinfo file the project cannot load without is generated by
libavr's tools/atmelstudio/componentinfo.py and ignored here, as are Studio's
output directories. Release is what the flag gate compares, the presets
defining no debug build; Debug carries the -Og -gdwarf-4 pair libavr's own
debug preset uses.

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

ide/fantemp.atsln

@@ -0,0 +1,22 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Atmel Studio Solution File, Format Version 11.00
+VisualStudioVersion = 14.0.23107.0
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{E66E83B9-2572-4076-B26E-6BE79FF3018A}") = "fantemp", "fantemp.cppproj", "{4F0C1D92-6A5B-4E33-9A71-2C8F5B0D47AE}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|AVR = Debug|AVR
+		Release|AVR = Release|AVR
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{4F0C1D92-6A5B-4E33-9A71-2C8F5B0D47AE}.Debug|AVR.ActiveCfg = Debug|AVR
+		{4F0C1D92-6A5B-4E33-9A71-2C8F5B0D47AE}.Debug|AVR.Build.0 = Debug|AVR
+		{4F0C1D92-6A5B-4E33-9A71-2C8F5B0D47AE}.Release|AVR.ActiveCfg = Release|AVR
+		{4F0C1D92-6A5B-4E33-9A71-2C8F5B0D47AE}.Release|AVR.Build.0 = Release|AVR
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+EndGlobal