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]/investigation/route.ts

@@ -2,22 +2,20 @@ export const dynamic = 'force-dynamic'
 
 import { NextRequest, NextResponse } from 'next/server'
 import { createClient } from '@/lib/supabase/server'
+import { getSession } from '@/lib/auth/get-session'
 
 export async function POST(
   request: NextRequest,
   { 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 { data: incident } = await supabase
     .from('incidents').select('status').eq('id', id).single()
   if (!incident) return NextResponse.json({ error: 'Not found' }, { status: 404 })
@@ -38,7 +36,7 @@ export async function POST(
     .from('investigations')
     .insert({
       incident_id: id,
-      investigator_id: user.id,
+      investigator_id: session.sub,
       method,
       findings_text: body.findings_text ?? null,
       root_cause_summary: body.root_cause_summary ?? null,
@@ -73,16 +71,13 @@ export async function PATCH(
   { 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 body = await request.json()
   const { investigation_id, complete, ...fields } = body