feat(auth): phase 3 — replace Supabase GoTrue with bcryptjs+jose

Custom auth stack: bcryptjs password hashing (cost 10, GoTrue-compatible),
jose JWT session cookies (edge-safe, 8hr TTL), new API routes for
login/logout/reset/change-password, middleware rewritten to JWT-only
verification with no DB access. All 38 protected pages and API routes
migrated from supabase.auth.getUser() to getSession(). Supabase .from()
queries retained for Phase 4. lib/db/index.ts refactored to lazy Proxy
singleton to avoid module-level throw during Next.js build.

tsc: clean, build: clean, tests: 4/4 passed

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

app/(protected)/admin/page.tsx

@@ -3,18 +3,17 @@ export const dynamic = 'force-dynamic'
 import Link from 'next/link'
 import { redirect } from 'next/navigation'
 import { createClient } from '@/lib/supabase/server'
+import { getSession } from '@/lib/auth/get-session'
 import { UserManager, type AdminUser, type SiteOption } from '@/components/admin/user-manager'
 import { SiteZoneManager, type SiteWithZones } from '@/components/admin/site-zone-manager'
 import { TruckManager, type Truck } from '@/components/admin/truck-manager'
 
 export default async function AdminHome() {
-  const supabase = await createClient()
-  const { data: { user } } = await supabase.auth.getUser()
-  if (!user) redirect('/login')
+  const session = await getSession()
+  if (!session) redirect('/login')
+  if (session.role !== 'admin') redirect('/login')
 
-  const { data: profile } = await supabase
-    .from('users').select('role').eq('id', user.id).single()
-  if (!profile || profile.role !== 'admin') redirect('/login')
+  const supabase = await createClient()
 
   const [{ data: users }, { data: sites }, { data: trucks }] = await Promise.all([
     supabase