M0: Floret skeleton — Material 3 Expressive scaffold over OpenTasks (planned)

Sibling to Calendula. Pure front-end posture; TaskContract data layer,
task screens and reminder engine to follow (see docs/PLAN.md).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/src/main/res/xml/backup_rules.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<full-backup-content>
+    <!-- No file-based backups; settings live in DataStore which is backed up by default. -->
+</full-backup-content>

app/src/main/res/xml/data_extraction_rules.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<data-extraction-rules>
+    <cloud-backup>
+        <!-- Allow DataStore backup, exclude nothing extra. -->
+    </cloud-backup>
+    <device-transfer>
+    </device-transfer>
+</data-extraction-rules>