Add a marketing landing hero and a live chain/round status strip

The user page's login screen was a bare test dashboard with no explanation
of how the lottery works; it now leads with a hero (3-step explainer, trust
pills) shown only while logged out, plus a bento-style nav and a glowing
round card during the draw.

Both the user and admin pages now show the current chain tip height and
lottery status (open / drawing / waiting for next round) via a small status
strip, polled from /rounds/current (extended with chain_tip_height sourced
from ElectrumListener.tip_height).

app/api/routes/rounds.py

@@ -1,6 +1,6 @@
 from datetime import timedelta, timezone
 
-from fastapi import APIRouter, Depends
+from fastapi import APIRouter, Depends, Request
 from pydantic import BaseModel
 from sqlalchemy import func, select
 from sqlalchemy.ext.asyncio import AsyncSession
@@ -24,16 +24,21 @@ class CurrentRoundResponse(BaseModel):
     draw_animation_seconds: int
     winner_user_id: int | None = None
     winner_amount_sats: int | None = None
+    chain_tip_height: int | None = None
 
 
 @router.get("/current", response_model=CurrentRoundResponse)
-async def current_round(session: AsyncSession = Depends(get_session)) -> CurrentRoundResponse:
+async def current_round(request: Request, session: AsyncSession = Depends(get_session)) -> CurrentRoundResponse:
     config = await get_round_config(session)
     round_ = await get_active_round(session)
+    listener = request.app.state.electrum_listener
+    chain_tip_height = listener.tip_height or None
     if round_ is None:
         await session.commit()
         return CurrentRoundResponse(
-            bet_amount_sats=config.bet_amount_sats, draw_animation_seconds=config.draw_animation_seconds
+            bet_amount_sats=config.bet_amount_sats,
+            draw_animation_seconds=config.draw_animation_seconds,
+            chain_tip_height=chain_tip_height,
         )
 
     participant_count = await session.scalar(
@@ -54,4 +59,5 @@ async def current_round(session: AsyncSession = Depends(get_session)) -> Current
         draw_animation_seconds=config.draw_animation_seconds,
         winner_user_id=round_.winner_user_id,
         winner_amount_sats=round_.winner_amount_sats,
+        chain_tip_height=chain_tip_height,
     )