Add CLAUDE.md with topic-specific context docs

Split project context into .claude/context/ (architecture, server,
styling, standards) instead of one large file, referenced from a
minimal root CLAUDE.md.

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

.claude/context/styling.md

@@ -0,0 +1,55 @@
+# Styling
+
+## Theme
+
+All theming goes through [`AppTheme`](../../lib/theme/app_theme.dart)
+(`AppTheme.light`/`AppTheme.dark`) — don't set colors/fonts ad hoc in
+widgets. Key points:
+
+- **Material 3**, seed-color based. `AppTheme.seedColors` is the picker list
+  users choose from; `defaultNextcloudBlue` (`#0082C9`) is the fallback.
+- **Dynamic color** (Android 12+ Material You / desktop accent color) is
+  supported via `package:dynamic_color`'s `DynamicColorBuilder` wrapping the
+  whole app in `main.dart`. When available and `useDynamicColor` is on, the
+  OS-provided `ColorScheme` wins over the seed color — always thread both
+  `dynamicScheme` and `useDynamicColor` through when adding a theme knob.
+- **Font**: Inter via `google_fonts`, applied through
+  `GoogleFonts.interTextTheme(...)`. In tests, set
+  `GoogleFonts.config.allowRuntimeFetching = false` in `setUpAll` — without
+  it, the font-fetch call to Google's CDN can stall `pumpAndSettle`
+  indefinitely (see `standards.md`).
+- **Cards**: flat (`elevation: 0`), 20px rounded corners,
+  `surfaceContainerLow`.
+- **App bars**: flat, not centered, `surface` background.
+- Two Flutter defaults are deliberately overridden app-wide rather than
+  per-widget, each with a comment explaining why in `app_theme.dart`:
+  Android predictive-back page transitions, and the non-2023 `SliderTheme`.
+  Follow that pattern (a themed default + a comment) instead of overriding
+  per-instance if you need the same behavior elsewhere.
+- Dark theme supports an `amoled` flag that flattens every surface tone to
+  pure black — extend `colorScheme.copyWith(...)` there if a new surface
+  role needs the same treatment, don't hardcode `Colors.black` at call sites.
+
+## Reusable chrome
+
+- [`FrostedGlassContainer`](../../lib/widgets/frosted_glass_container.dart) —
+  the blurred/translucent pill background shared by all floating chrome
+  (bottom nav bar, media-viewer action bar). Reuse this for any new floating
+  overlay instead of building a new blur/shadow combo.
+- [`FloatingBottomNavBar`](../../lib/widgets/floating_bottom_bar.dart) — the
+  main tab bar; opacity/blur are user-adjustable settings
+  (`ServerProvider.bottomBarOpacity`/`bottomBarBlur`), not constants — pull
+  new adjustable visual knobs from the provider the same way rather than
+  hardcoding them.
+- Icons: prefer `Icons.*_rounded` (matches the rest of the app) or
+  `material_symbols_icons` where Material Symbols are already in use; avoid
+  mixing in the sharp/outlined default set.
+
+## Conventions
+
+- No hardcoded colors for anything themeable — pull from
+  `Theme.of(context).colorScheme`, not `Colors.blue` etc. (per-file-type
+  icon tinting in `files_view.dart`'s `_getIconColor` is the one deliberate
+  exception, since those colors are content-identity cues, not theme).
+- Use `colorScheme.surfaceContainer*`/`onSurfaceVariant` tokens for
+  elevation/secondary text rather than manual opacity on black/white.