chore: add Flutter Version Manager configuration (#239)

* chore: add Flutter Version Manager configuration

* chore: apply diffs generated by `fvm use`

* docs: update README to include FVM setup instructions for Flutter

* docs: update FVM setup instructions in README for clarity

---------

Co-authored-by: Lily <[email protected]>

.fvmrc

@@ -0,0 +1,3 @@
+{
+  "flutter": "3.7.12"
+}

.gitignore

@@ -56,4 +56,7 @@ app.*.map.json
 /android/app/release
 
 # Test files
-**/test/ischool_plus_connector_test/credential.json
+**/test/ischool_plus_connector_test/credential.json
+
+# FVM Version Cache
+.fvm/

.vscode/settings.json

@@ -1,12 +1,17 @@
 {
   "dart.lineLength": 120,
+  "dart.flutterSdkPath": ".fvm/versions/3.7.12",
   "[dart]": {
-    "editor.rulers": [120]
+    "editor.rulers": [
+      120
+    ]
   },
   "markdownlint.ignore": ".gitignore",
   "[markdown]": {
     "editor.wordWrap": "bounded",
     "editor.wordWrapColumn": 120,
-    "editor.rulers": [120]
+    "editor.rulers": [
+      120
+    ]
   }
-}
+}

README.md

@@ -134,7 +134,15 @@ Once all dependencies are successfully installed (excluding `tat_core`), you can
 > Otherwise, you will not be able to build successfully. For information on how to join the **NPC**, please refer to the
 > Contact Us section below.
 
-If you got any questions during the above steps, please feel free to contact us (NPC) anytime.
+## Using FVM to Install Flutter
+
+To set up FVM and Flutter 3.7.12 (our last supported version):
+
+1. Follow the [instructions](https://fvm.app/documentation/getting-started/installation) to install FVM.
+1. Run `fvm use` in the project directory to install the Flutter version specified in `.fvmrc`.
+1. Use `fvm flutter --version` to verify that Flutter is correctly installed.
+
+If you have any questions during the above steps, please feel free to contact us (NPC) anytime.
 
 ## Discussion