fix: event colors/null parsing, edit+copy, settings chips, scroll perf, splash

- CalEvent parsing: handle Android's JSONObject.optString JSON-null quirk that
  returned the string "null" — this made every event blue (color "null" →
  fallback) and showed "null" for empty location/description. Now null-safe.
- Event detail: copy-to-calendar action; calendar row uses a calendar icon
  (was identical to the notes icon); empty location/notes rows hidden
- Event editor: copy mode (prefill from an existing event, save as new)
- Settings: hour height, text/line contrast are now button chips (like the
  cache range); color picker wraps, shows the current colour and a check mark
- Month scroll perf: precompute a day→events index once per change and only
  reload when the visible month actually changes (was filtering every cell
  every frame → laggy)
- Splash: dark window/splash background + inset launcher icon (was an ugly
  white box on startup)

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

app/src/main/java/com/scarriffle/calendarr/ui/L10n.kt

@@ -53,10 +53,16 @@ object L10n {
             "settings.color.accent" to "Akzentfarbe", "settings.color.today" to "Heutige-Tag-Farbe",
             "settings.color.divider" to "Monatswechsel-Linie", "settings.color.label" to "Monatskürzel",
             "settings.textcontrast" to "Schriftkontrast", "settings.linecontrast" to "Linienkontrast",
+            "settings.contrast.dark" to "Dunkel", "settings.contrast.medium" to "Mittel",
+            "settings.contrast.bright" to "Hell", "settings.contrast.max" to "Maximum",
+            "settings.linecontrast.barely" to "Kaum", "settings.linecontrast.subtle" to "Subtil",
+            "settings.linecontrast.normal" to "Normal", "settings.linecontrast.strong" to "Stark",
             "settings.calview" to "Kalenderansicht", "settings.defaultview" to "Standardansicht",
             "settings.firstweekday" to "Erster Wochentag", "settings.monday" to "Montag",
             "settings.sunday" to "Sonntag", "settings.dimpast" to "Vergangene Termine ausgrauen",
             "settings.hourheight" to "Stundenhöhe",
+            "settings.hourheight.compact" to "Kompakt", "settings.hourheight.normal" to "Normal",
+            "settings.hourheight.comfort" to "Komfort", "settings.hourheight.large" to "Gross",
             "common.cancel" to "Abbrechen", "common.close" to "Schliessen",
             "common.ok" to "OK", "common.error" to "Fehler", "common.delete" to "Löschen",
             "common.save" to "Sichern", "common.retry" to "Erneut versuchen",
@@ -88,6 +94,7 @@ object L10n {
             "event.calendar_picker" to "Kalender", "event.color_section" to "Farbe",
             "event.color" to "Terminfarbe", "event.reset_color" to "Zurücksetzen",
             "event.edit_title" to "Termin bearbeiten", "event.new_title" to "Neuer Termin",
+            "event.copy_title" to "Termin kopieren", "event.copy_to" to "In Kalender kopieren",
             "event.save" to "Sichern", "event.add" to "Hinzufügen",
             "event.delete_confirm" to "Diesen Termin löschen?",
             "accounts.title" to "Konten", "accounts.loading" to "Lade Konten…",
@@ -146,10 +153,16 @@ object L10n {
             "settings.color.accent" to "Accent color", "settings.color.today" to "Today color",
             "settings.color.divider" to "Month divider line", "settings.color.label" to "Month abbreviation",
             "settings.textcontrast" to "Text contrast", "settings.linecontrast" to "Line contrast",
+            "settings.contrast.dark" to "Dark", "settings.contrast.medium" to "Medium",
+            "settings.contrast.bright" to "Bright", "settings.contrast.max" to "Maximum",
+            "settings.linecontrast.barely" to "Barely", "settings.linecontrast.subtle" to "Subtle",
+            "settings.linecontrast.normal" to "Normal", "settings.linecontrast.strong" to "Strong",
             "settings.calview" to "Calendar view", "settings.defaultview" to "Default view",
             "settings.firstweekday" to "First day of week", "settings.monday" to "Monday",
             "settings.sunday" to "Sunday", "settings.dimpast" to "Dim past events",
             "settings.hourheight" to "Hour height",
+            "settings.hourheight.compact" to "Compact", "settings.hourheight.normal" to "Normal",
+            "settings.hourheight.comfort" to "Comfort", "settings.hourheight.large" to "Large",
             "common.cancel" to "Cancel", "common.close" to "Close",
             "common.ok" to "OK", "common.error" to "Error", "common.delete" to "Delete",
             "common.save" to "Save", "common.retry" to "Retry",
@@ -181,6 +194,7 @@ object L10n {
             "event.calendar_picker" to "Calendar", "event.color_section" to "Color",
             "event.color" to "Event color", "event.reset_color" to "Reset",
             "event.edit_title" to "Edit event", "event.new_title" to "New event",
+            "event.copy_title" to "Copy event", "event.copy_to" to "Copy to calendar",
             "event.save" to "Save", "event.add" to "Add",
             "event.delete_confirm" to "Delete this event?",
             "accounts.title" to "Accounts", "accounts.loading" to "Loading accounts…",