Switch to fvm

This tracks the used Flutter SDK version compatible with the [fvm][1]
Flutter version management tool.

It allows to make the build reproducible. The build documentation is
adapted and the used Flutter version committed.

[1]: https://fvm.app

3 files changed, 9 insertions, 3 deletions

diff --git a/.fvmrc b/.fvmrc
new file mode 100644
index 0000000..0168639
--- /dev/null
+++ b/.fvmrc
@@ -0,0 +1,3 @@
+{
+  "flutter": "3.41.7"
+}
\ No newline at end of file
diff --git a/.gitignore b/.gitignore
index 3820a95..ac83f76 100644
--- a/.gitignore
+++ b/.gitignore
@@ -43,3 +43,6 @@ app.*.map.json
 /android/app/debug
 /android/app/profile
 /android/app/release
+
+# FVM Version Cache
+.fvm/
\ No newline at end of file
diff --git a/README.md b/README.md
index 1eb442b..29234ea 100644
--- a/README.md
+++ b/README.md
@@ -5,14 +5,14 @@
 The app can be run in debug mode allowing a hot-reload.
 
 ```
-flutter run
+fvm flutter run
 ```
 
 A release version can be built for all the targets individually.
 
 ```
-flutter build linux
-flutter build apk
+fvm flutter build linux
+fvm flutter build apk
 ```
 
 ## Icon maintenance