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>

lib/auth/get-session.ts

@@ -0,0 +1,10 @@
+import 'server-only'
+import { cookies } from 'next/headers'
+import { verifySession, type SessionPayload } from './session'
+
+export async function getSession(): Promise<SessionPayload | null> {
+  const cookieStore = await cookies()
+  const token = cookieStore.get('ims_session')?.value
+  if (!token) return null
+  return verifySession(token)
+}

lib/auth/password.ts

@@ -0,0 +1,11 @@
+import bcryptjs from 'bcryptjs'
+
+const BCRYPT_ROUNDS = 10  // matches Supabase GoTrue default
+
+export async function hashPassword(plaintext: string): Promise<string> {
+  return bcryptjs.hash(plaintext, BCRYPT_ROUNDS)
+}
+
+export async function verifyPassword(plaintext: string, hash: string): Promise<boolean> {
+  return bcryptjs.compare(plaintext, hash)
+}

lib/auth/require-admin.ts

@@ -1,18 +1,12 @@
-import { createClient } from '@/lib/supabase/server'
-import type { SupabaseClient } from '@supabase/supabase-js'
-import type { User } from '@supabase/supabase-js'
+import { getSession } from '@/lib/auth/get-session'
+import type { SessionPayload } from '@/lib/auth/session'
 
 // Shared guard for /api/admin/* routes: resolves the session and requires
-// the admin role. Returns user: null when the caller must respond 403.
+// the admin role. Returns session: null when the caller must respond 403.
 export async function requireAdmin(): Promise<{
-  supabase: SupabaseClient
-  user: User | null
+  session: SessionPayload | null
 }> {
-  const supabase = await createClient()
-  const { data: { user }, error } = await supabase.auth.getUser()
-  if (error || !user) return { supabase, user: null }
-  const { data: profile } = await supabase
-    .from('users').select('role').eq('id', user.id).single()
-  if (!profile || profile.role !== 'admin') return { supabase, user: null }
-  return { supabase, user }
+  const session = await getSession()
+  if (!session || session.role !== 'admin') return { session: null }
+  return { session }
 }

lib/auth/session.ts

@@ -0,0 +1,37 @@
+import { SignJWT, jwtVerify, type JWTPayload } from 'jose'
+
+const SESSION_COOKIE = 'ims_session'
+const SESSION_TTL_SECONDS = 8 * 60 * 60  // 8 hours
+
+export { SESSION_COOKIE }
+
+function getSecret(): Uint8Array {
+  const secret = process.env.JWT_SECRET
+  if (!secret) throw new Error('JWT_SECRET not configured')
+  return new TextEncoder().encode(secret)
+}
+
+export interface SessionPayload {
+  sub: string      // user id (UUID)
+  role: string     // user_role enum value
+  siteId: string | null
+  name: string
+}
+
+export async function createSession(payload: SessionPayload): Promise<string> {
+  return new SignJWT({ ...payload } as JWTPayload)
+    .setProtectedHeader({ alg: 'HS256' })
+    .setIssuedAt()
+    .setExpirationTime(`${SESSION_TTL_SECONDS}s`)
+    .sign(getSecret())
+}
+
+/** Verify and decode a JWT. Returns null on invalid/expired. */
+export async function verifySession(token: string): Promise<SessionPayload | null> {
+  try {
+    const { payload } = await jwtVerify(token, getSecret())
+    return payload as unknown as SessionPayload
+  } catch {
+    return null
+  }
+}