feat: initial FitCoach Pro lead management app

Next.js 16 app with full CRUD lead management:
- REST API (/api/leads) with GET (pagination), POST, PUT, DELETE (soft delete)
- Zod validation (server + client), Supabase (PostgreSQL)
- Responsive UI: leads table (desktop) + cards (mobile), modal form, toast notifications
- 43 tests (Vitest + React Testing Library): validation, components, pagination
- Docker setup (multi-stage build, health check)
- Supabase migration + 15 seed leads
- Documentation (CLAUDE.md, README, API docs)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Dockerfile

@@ -0,0 +1,48 @@
+# Stage 1: Install dependencies
+FROM node:22-alpine AS deps
+RUN corepack enable && corepack prepare pnpm@latest --activate
+WORKDIR /app
+COPY package.json pnpm-lock.yaml ./
+RUN pnpm install --frozen-lockfile
+
+# Stage 2: Build the application
+FROM node:22-alpine AS builder
+RUN corepack enable && corepack prepare pnpm@latest --activate
+WORKDIR /app
+COPY --from=deps /app/node_modules ./node_modules
+COPY . .
+
+ARG NEXT_PUBLIC_SUPABASE_URL
+ARG NEXT_PUBLIC_SUPABASE_ANON_KEY
+
+ENV NEXT_PUBLIC_SUPABASE_URL=$NEXT_PUBLIC_SUPABASE_URL
+ENV NEXT_PUBLIC_SUPABASE_ANON_KEY=$NEXT_PUBLIC_SUPABASE_ANON_KEY
+ENV NEXT_TELEMETRY_DISABLED=1
+
+RUN pnpm build
+
+# Stage 3: Production runner
+FROM node:22-alpine AS runner
+WORKDIR /app
+
+ENV NODE_ENV=production
+ENV NEXT_TELEMETRY_DISABLED=1
+
+RUN addgroup --system --gid 1001 nodejs
+RUN adduser --system --uid 1001 nextjs
+
+COPY --from=builder /app/public ./public
+COPY --from=builder --chown=nextjs:nodejs /app/.next/standalone ./
+COPY --from=builder --chown=nextjs:nodejs /app/.next/static ./.next/static
+
+USER nextjs
+
+EXPOSE 3000
+
+ENV PORT=3000
+ENV HOSTNAME="0.0.0.0"
+
+HEALTHCHECK --interval=30s --timeout=3s --start-period=10s --retries=3 \
+  CMD wget --no-verbose --tries=1 --spider http://localhost:3000/ || exit 1
+
+CMD ["node", "server.js"]