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/supabase/storage.ts

@@ -18,11 +18,8 @@ export async function uploadEvidenceFile(
   file: File,
   incidentId: string,
   stage: EvidenceStage,
+  userId: string,
 ): Promise<{ path: string; publicUrl: string; hash: string }> {
-  const { data, error: authError } = await supabase.auth.getUser()
-  if (authError || !data?.user) throw new Error('Not authenticated')
-  const user = data.user
-
   // Server-side size limit before processing
   const isVideo = file.type.startsWith('video/')
   const maxBytes = isVideo ? 200 * 1024 * 1024 : 10 * 1024 * 1024
@@ -40,7 +37,7 @@ export async function uploadEvidenceFile(
 
   const ext = detected?.ext ?? file.name.split('.').pop() ?? 'bin'
   const filename = `${Date.now()}-${Math.random().toString(36).slice(2)}.${ext}`
-  const path = `${user.id}/${incidentId}/${stage}/${filename}`
+  const path = `${userId}/${incidentId}/${stage}/${filename}`
 
   const hash = await computeHashFromBuffer(buffer)