feat: adopt material 3 theme and billing adjustments

doc/plan_color.md

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+# Color & Theme Plan (Material 3)
+
+Goals
+- Remove Glassmorphism. Use Material 3 ColorScheme/typography/shape/elevation consistently.
+- Ensure light/dark/system modes with accessible contrast; no dark-on-dark text.
+- Semantic colors: primary/secondary/info/success/warning/error.
+
+Phases
+1) Audit + Baseline
+- Inventory AppColors and Glass usages; map to ColorScheme.
+- Set `ColorScheme.error=#EF4444` (light/dark) and verify Snackbar uses.
+
+2) Core Components
+- Settings: unify to `onSurface/onSurfaceVariant/primary` and fix Switch deprecations.
+- Home Summary: surface/elevation + on-colors; badges use surfaceContainer variants.
+- Add Subscription: selectors/fields to M3; disable glass flags.
+
+3) Analysis & Lists
+- Charts: grid/labels to onSurfaceVariant; tooltips to inverseSurface.
+- Event/Detail sections: containers to surface + outline; text/icons to onSurface.
+
+4) Theme & Cleanup
+- Refactor `app_theme.dart` to remove glass defaults; prefer ColorScheme-driven themes.
+- Replace remaining hard-coded colors (AppColors.*) with scheme; keep gradients sparingly.
+- Resolve lints: const constructors, deprecated APIs (activeColor, scale).
+
+Validation
+- Run `scripts/check.sh` every change.
+- Visual check in light/dark/system; confirm no low-contrast text.
+
+Current Status (2025-09-10)
+- Settings screen updated to ColorScheme; Switch deprecations fixed.
+- AddSubscription selectors use M3 (glass flags off).
+- MainSummaryCard event-savings text = primary.
+- Monthly chart tooltips use inverseSurface/onInverseSurface.
+- Next: theme/app_theme.dart cleanup; remaining AppColors usages; chart palette alignment.
+ 
+Current Status (2025-09-11)
+- Billing/Currency/Category selectors: use ColorScheme (selected=primary/onPrimary, unselected=surface+outline, text=onSurface). Glass/grad props deprecated and ignored.
+- AnalysisBadge: remove AppColors, use surface + outline + subtle shadow.
+- SubscriptionCard: header strip uses error/warning/category; price and badges use ColorScheme (error/primary/onSurfaceVariant); due-chip uses success/warning extension; removed hard-coded reds/grays.
+- Checks: scripts/check.sh passes (format/analyze/test).
+- Next: migrate remaining AppColors usages (detail sections, snackbars, splash), reduce hard-coded Colors in adaptive_theme.dart, optional: revisit success/warning harmonization.
+
+Update (2025-09-11, PM)
+- DetailEventSection: replaced green constants with ColorScheme.success; onPrimary for pill text.
+- AddSubscriptionEventSection: info boxes use tertiary; removed AppColors.
+- SMS Scan widgets: progress/button now use ColorScheme.primary.
+- SubscriptionPieChartCard: no AppColors; chart palette uses scheme.success/warning; in-chart labels are white; exchange-rate chip uses primary soft background/border.
+- EventAnalysisCard: discount/current price and discount badge use scheme.success/error.
+- TotalExpenseSummaryCard: success icon uses scheme.success.
+- AppLock/Main screen SnackBars: unified to scheme.error/success with onPrimary text.
+- Splash: overlay/particles/title/subtitle/progress use ColorScheme; particle color bound to scheme.primary.
+- Checks: scripts/check.sh passes.
+
+Update (2025-09-11, PM-2)
+- Dark Theme(adaptive_theme.dart): replaced hard-coded widget colors with ColorScheme-driven values.
+  - Inputs: fill=surface, borders=outline/primary/error, labels/hints=onSurfaceVariant.
+  - Buttons/Switch/Checkbox/Radio/Slider/TabBar/Divider: all use scheme tokens.
+  - AppBar/Card: background=surface, foreground/on-colors from scheme.
+  - OLED: inherits dark with surface override only.
+- Checks: scripts/check.sh passes (no issues).
+
+Update (2025-09-11, PM-3)
+- Light Theme(app_theme.dart): AppColors 의존을 ColorScheme 사용으로 축소.
+  - InputDecorationTheme: fill=surface, border=outline/primary/error, label/hint=onSurfaceVariant.
+  - Buttons/FAB: primary/onPrimary, Outlined side=outline.
+  - SnackBarTheme: primary/onPrimary.
+  - Scaffold background 유지(#F1F5F9) — ColorScheme.background 대신 직접 지정.
+- Checks: scripts/check.sh passes.