feat: HA/Google edit, full-page event detail, KW+zigzag divider, HSV picker, splash

- Home Assistant & Google events now editable/deletable (server PUT/DELETE
  endpoints wired; saveEvent had no HA/Google update branch -> created dupes)
- Event detail is now a full screen (Scaffold) instead of a bottom sheet:
  long notes scroll, action buttons no longer hidden behind the system nav bar;
  distinct calendar vs notes icons
- Month view: calendar-week number on Mondays, month-boundary divider with
  zigzag step (month_divider_color), month label in month_label_color,
  text/line contrast applied
- Compact top bar with smaller title; prev/next chevrons present in month view
  and scroll one month at a time
- Real HSV colour picker (SV field + hue slider + hex) for primary, accent,
  today, month-divider and month-label colours
- Black status/navigation bars; portrait-locked; crisp custom splash with app
  name, high-res icon and © Scarriffle

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

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

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<!-- The launcher icon inset so it sits comfortably inside the round splash mask. -->
+<!-- High-res logo inset so it sits comfortably inside the round splash mask. -->
 <inset xmlns:android="http://schemas.android.com/apk/res/android"
-    android:drawable="@mipmap/ic_launcher"
+    android:drawable="@drawable/ic_splash_logo"
     android:inset="18%" />