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/dashboard/ai/risk-flags/route.ts

@@ -2,6 +2,7 @@ export const dynamic = 'force-dynamic'
 
 import { NextResponse } from 'next/server'
 import { createClient } from '@/lib/supabase/server'
+import { getSession } from '@/lib/auth/get-session'
 import { createDeepSeekClient } from '@/lib/claude/client'
 import { getApiKey } from '@/lib/settings'
 
@@ -18,14 +19,13 @@ type ZoneAggregate = {
 }
 
 export async function POST() {
-  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', 'management'].includes(profile.role))
+  const session = await getSession()
+  if (!session) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+  if (!['hse', 'admin', 'management'].includes(session.role))
     return NextResponse.json({ error: 'Forbidden' }, { status: 403 })
 
+  const supabase = await createClient()
+
   const now = new Date()
   const ninetyDaysAgo = new Date(now)
   ninetyDaysAgo.setDate(now.getDate() - 90)
@@ -82,7 +82,7 @@ export async function POST() {
   const { data: lastCall } = await supabase
     .from('audit_log')
     .select('changed_at')
-    .eq('changed_by', user.id)
+    .eq('changed_by', session.sub)
     .eq('action', 'ai_risk_flags')
     .order('changed_at', { ascending: false })
     .limit(1)
@@ -166,7 +166,7 @@ ${JSON.stringify(aggregates, null, 2)}
 
   await supabase.rpc('write_audit_log', {
     p_table_name: 'incidents',
-    p_record_id: user.id,
+    p_record_id: session.sub,
     p_action: 'ai_risk_flags',
     p_new_value: { flags, summary: input.summary, model: 'deepseek-chat' } as never,
   })