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/api/incidents/[id]/similar/route.ts

@@ -2,6 +2,7 @@ export const dynamic = 'force-dynamic'
 
 import { NextRequest, NextResponse } from 'next/server'
 import { createClient } from '@/lib/supabase/server'
+import { getSession } from '@/lib/auth/get-session'
 import { embedText } from '@/lib/claude/embed'
 import { getApiKey } from '@/lib/settings'
 
@@ -10,14 +11,13 @@ export async function GET(
   { params }: { params: Promise<{ id: string }> }
 ) {
   const { id } = await params
-  const supabase = await createClient()
-  const { data: { user }, error: authError } = await supabase.auth.getUser()
-  if (authError || !user) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
-
-  const { data: profile } = await supabase.from('users').select('role').eq('id', user.id).single()
-  if (!profile || !['hse', 'admin'].includes(profile.role))
+  const session = await getSession()
+  if (!session) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+  if (!['hse', 'admin'].includes(session.role))
     return NextResponse.json({ error: 'Forbidden' }, { status: 403 })
 
+  const supabase = await createClient()
+
   const googleAiKey = await getApiKey(supabase, 'GOOGLE_AI_API_KEY')
 
   const { data: incident } = await supabase