Add the Rippr Flutter port: source, history bundle, and installable APK

The port runs on Android and iOS and is feature-complete; the native Android app
is superseded but kept, since it is still the only version that has recorded real
rides.

rippr-flutter-1.0-debug.apk is package com.rippr.port, deliberately different
from the native com.rippr so both install side by side. Recording the same ride
on both at once is the strongest available check that the port is faithful.

Added INSTALL.md covering both platforms. Android is a one-line adb install; iOS
has no APK equivalent and must be built and signed through Xcode with a free
Apple ID, which gives a 7-day profile.

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

rippr-flutter-src/.metadata

@@ -0,0 +1,33 @@
+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: "4cf24164269a5ebf0c16a028a00727d0e77bbb05"
+  channel: "stable"
+
+project_type: app
+
+# Tracks metadata for the flutter migrate command
+migration:
+  platforms:
+    - platform: root
+      create_revision: 4cf24164269a5ebf0c16a028a00727d0e77bbb05
+      base_revision: 4cf24164269a5ebf0c16a028a00727d0e77bbb05
+    - platform: android
+      create_revision: 4cf24164269a5ebf0c16a028a00727d0e77bbb05
+      base_revision: 4cf24164269a5ebf0c16a028a00727d0e77bbb05
+    - platform: ios
+      create_revision: 4cf24164269a5ebf0c16a028a00727d0e77bbb05
+      base_revision: 4cf24164269a5ebf0c16a028a00727d0e77bbb05
+
+  # User provided section
+
+  # List of Local paths (relative to this file) that should be
+  # ignored by the migrate tool.
+  #
+  # Files that are not part of the templates will be ignored by default.
+  unmanaged_files:
+    - 'lib/main.dart'
+    - 'ios/Runner.xcodeproj/project.pbxproj'