Add interactive citizen page with sidebar, display settings, and adaptive CSS

Major rework of the citizen-facing page:
- Chart + sidebar layout (auth/vote/countdown in right sidebar)
- DisplaySettings component (font size, chart density, color palettes)
- Adaptive CSS with clamp() throughout, responsive breakpoints at 480/768/1024
- Baseline charts zoomed on first tier for small consumption detail
- Marginal price chart with dual Y-axes (foyers left, €/m³ right)
- Key metrics banner (5 columns: recettes, palier, prix palier, prix médian, mon prix)
- Client-side p0/impacts computation, draggable median price bar
- Household dots toggle, vote overlay curves
- Auth returns volume_m3, vote captures submitted_at
- Cleaned header nav (removed Accueil/Super Admin for public visitors)
- Terminology: foyer for bills, électeur for votes
- 600m³ added to impact reference volumes
- Realistic seed votes (50 votes, 3 profiles)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/routers/communes.py

@@ -2,13 +2,16 @@ from fastapi import APIRouter, Depends, HTTPException
 from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy import select, delete
 
+from datetime import datetime
+
 from app.database import get_db
 from app.models import Commune, TariffParams, Household, Vote, CommuneContent, AdminUser, admin_commune_table
 from app.schemas import (
     CommuneCreate, CommuneUpdate, CommuneOut,
-    TariffParamsUpdate, TariffParamsOut,
+    TariffParamsUpdate, TariffParamsOut, PublishCurveRequest,
 )
 from app.services.auth_service import get_current_admin, require_super_admin
+from app.engine.pricing import HouseholdData, compute_p0
 
 router = APIRouter()
 
@@ -128,3 +131,49 @@ async def update_params(
     await db.commit()
     await db.refresh(params)
     return params
+
+
+@router.post("/{slug}/params/publish", response_model=TariffParamsOut)
+async def publish_curve(
+    slug: str,
+    data: PublishCurveRequest,
+    db: AsyncSession = Depends(get_db),
+    admin: AdminUser = Depends(get_current_admin),
+):
+    """Admin publishes a Bézier curve as the commune's reference."""
+    result = await db.execute(
+        select(TariffParams).join(Commune).where(Commune.slug == slug)
+    )
+    params = result.scalar_one_or_none()
+    if not params:
+        raise HTTPException(status_code=404, detail="Paramètres introuvables")
+
+    # Compute p0 for this curve
+    hh_result = await db.execute(
+        select(Household).join(Commune).where(Commune.slug == slug)
+    )
+    households_db = hh_result.scalars().all()
+    households = [
+        HouseholdData(volume_m3=h.volume_m3, status=h.status, price_paid_eur=h.price_paid_eur)
+        for h in households_db
+    ]
+
+    p0 = compute_p0(
+        households,
+        recettes=params.recettes, abop=params.abop, abos=params.abos,
+        vinf=data.vinf, vmax=params.vmax, pmax=params.pmax,
+        a=data.a, b=data.b, c=data.c, d=data.d, e=data.e,
+    )
+
+    params.published_vinf = data.vinf
+    params.published_a = data.a
+    params.published_b = data.b
+    params.published_c = data.c
+    params.published_d = data.d
+    params.published_e = data.e
+    params.published_p0 = p0
+    params.published_at = datetime.utcnow()
+
+    await db.commit()
+    await db.refresh(params)
+    return params