UI buildout: today screen, med editor with FEST autocomplete, schedule editor, settings

Milestone 9. Hand-rolled back-stack navigation (4 screens don't justify
navigation-compose). DoseActions is now the single implementation of
Taken/Snooze/Skip/Undo shared by notification receiver and UI — two
code paths for 'taken' would eventually disagree about inventory.
Screens read DAO Flows directly; every schedule mutation re-arms
alarms via armAll() (idempotent, OS-deduplicated). One-time battery
prompt + POST_NOTIFICATIONS request on the today screen. Settings:
S3/Garage config, typed-passphrase export/import (replace-all import
re-arms alarms), FEST refresh, PDF share. TalkBack: merged semantics
with full descriptions on dose cards, content descriptions on icon
buttons and day chips. Doctor PDF locale pinned to Bokmål — verified
on emulator after catching English month names on an en-US device.

Emulator-verified end-to-end: battery prompt → system dialog, med
created via editor (validation catches bad input), dose time added →
exact alarm armed immediately, Ta nå → TAKEN + inventory 20→19 +
reactive UI update, Angre → PENDING + inventory restored, settings
renders, PDF generated and share sheet opened.

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

app/src/main/res/drawable/ic_back.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp" android:height="24dp"
+    android:viewportWidth="24" android:viewportHeight="24"
+    android:autoMirrored="true"
+>
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M20,11H7.83l5.59,-5.59L12,4l-8,8 8,8 1.41,-1.41L7.83,13H20v-2z" />
+</vector>