feat: restructure styles and components for improved design system

- Added typography and design system styles to globals.css.
- Removed deprecated home.css and landing.css files.
- Introduced DiscordSignInButton component for Discord authentication.
- Created Card and CardGrid components for structured content display.
- Implemented ContainerShowcase to demonstrate card usage and layout.
- Added DesignSystemTabs for navigation between design system sections.
- Established typography.css for consistent text styling across components.
- Added tests for typography styles to ensure compliance with design standards.

README.md

@@ -1,7 +1,7 @@
 # Minabot
 
 Bun + Hono habit-tracking REST API with Drizzle ORM and local SQLite. The existing
-React Router client has a public landing page and a connected signed-in habit dashboard.
+React Router client currently contains only the design system, ready for a fresh page redesign.
 
 See [the REST API reference](docs/API.md) for habits, task recurrence, dated progress,
 combined calendars, historical corrections, daily resets, and optional count carryover.
@@ -13,12 +13,17 @@ bun dev
 
 Open http://127.0.0.1:3000. Set `PORT` to use a different port.
 
-- Client pages: `/`, `/about`, `/settings`.
+- Client page: `/design-system`. Root and all other client URLs redirect there.
 - Hono endpoint: `GET /api/health`.
 - Unknown API routes return JSON with a 404 status.
 
 ### Design system preview
 
+The library uses seven tabs: Foundations, Components, Layout, Calendars, Playground,
+Editing, and References. Foundations is the default. Each tab has a URL hash;
+existing section links still work. Arrow keys, Home, and End navigate the tabs.
+Switching tabs preserves unsaved demo state; browser back/forward restores the section.
+
 Open `/design-system#editing` for interactive habit settings, task recurrence,
 and dated progress corrections. Habit colors include Earth, Coast, Dusk, Forest,
 Citrus, Blossom, Jewel, and Slate palettes plus a native picker and hex input. Editors support save/cancel,
@@ -30,39 +35,24 @@ clears the preview. Habit colors preview immediately across the editor and the
 daily/detail charts; Save keeps the color in the demo and Cancel restores it.
 Other settings and progress remain independent of the daily tracking playground.
 
-Signed-out visitors at `/` see the landing page, with interactive habit calendars
-reused from the design system, a how-it-works introduction, and Discord sign-in.
-The demo is local, unsaved state and never writes to the habit API. Account loading
-and retryable errors are resolved before choosing the public or signed-in home.
-Signing out updates the shared account state and reveals the landing page immediately.
-Discord integration currently covers identity only, not bot commands or reminders.
+The previous Landing, Home, About, and Settings pages have been removed. The
+backend API, authentication infrastructure, database, and reusable components remain
+available for the redesigned pages. The design system does not load account data
+or call the API.
 
-Signed-in users at `/` get a personalized home with their Discord avatar, tracking
-date/timezone, daily completion summary, manual/count/task check-ins, a remaining
-filter, and per-habit calendar history in the design system's two-column chart grid.
-Each habit has its own heading, schedule, color key, and compact calendar. Daily
-check-ins use compact rows with expandable tasks. New accounts get editable starter ideas and
-a create-habit dialog supporting all three methods, all schedule types, and the shared
-palette/custom color picker. The habit and its color are saved atomically. Progress
-is saved through the habit API; history uses server-provided progress colors and dated units,
-never the landing page's demo data. Visible dashboards refresh every minute and on
-returning to the tab. Loading, retry, expired-session, no-schedule, and all-complete
-states are handled separately. Each habit has Edit and Delete controls: edit its name,
-count target/unit, schedule, and color, or confirm removal from the dashboard using
-the existing archive API, which retains recorded history. Editing keeps the tracking
-method and existing tasks intact. Unscheduled dates use neutral dots; upcoming dates
-share the zero-progress fill while retaining their distinct inspection labels.
-Archive management, task-definition editing, historical corrections, and saved
-combined-chart management remain outside this home view.
+`styles/globals.css` is the only stylesheet
+entry point; component styles are in Tailwind's components layer so utilities can
+override them predictably. Tailwind Preflight remains omitted.
 
-For isolated browser QA, run `bun scripts/dashboard-preview.ts` and open the printed
-preview login URL. It serves the real UI and API against an in-memory test database,
-uses a separate test cookie, and discards its data on exit.
-It is a local test harness, not a production sign-in flow.
-
-Secondary pages retain a heading, native navigation buttons, and account controls. Tailwind utilities
-and shadcn configuration are available; Tailwind Preflight is omitted to preserve
-native browser styling.
+`styles/typography.css` defines reusable Tailwind classes: `type-display` (72/81),
+`type-section` (48/54), `type-title` (32/40), `type-lead` (20/30), `type-body`
+(16/24), `type-small` and `type-label` (14/21), and `type-control` (24/30, symbols).
+Values are font-size/line-height in pixels at the default 16px root, implemented
+in rem. At 640px and below, display steps to 48/54 and section to 36/45; body and
+supporting text never shrink. Use these classes directly or with `@apply`, not
+bespoke font sizes or viewport-based type. See `/design-system#foundations` for
+live specimens. Reuse `SectionHeading`, `Button`, `ButtonLink`, and the shared
+`DiscordSignInButton` for headings and calls to action.
 
 ```sh
 bun run typecheck