Add Zod validation, fix mass assignment, remove test endpoints and dead code

- Add centralized Zod schemas (server/utils/schemas.js) and validateBody
  utility for all API endpoints
- Fix critical mass assignment in member creation: raw body no longer
  passed to new Member(), only validated fields (email, name, circle,
  contributionTier) are accepted
- Apply Zod validation to login, profile patch, event registration,
  updates, verify-payment, and admin event creation endpoints
- Fix logout cookie flags to match login (httpOnly: true, secure
  conditional on NODE_ENV)
- Delete unauthenticated test/debug endpoints (test-connection,
  test-subscription, test-bot)
- Remove sensitive console.log statements from Helcim and member
  endpoints
- Remove unused bcryptjs dependency
- Add 10MB file size limit on image uploads
- Use runtime config for JWT secret across all endpoints
- Add 38 validation tests (117 total, all passing)

server/api/updates/index.get.js

@@ -11,7 +11,7 @@ export default defineEventHandler(async (event) => {
   // Check if user is authenticated
   if (token) {
     try {
-      const decoded = jwt.verify(token, process.env.JWT_SECRET);
+      const decoded = jwt.verify(token, useRuntimeConfig().jwtSecret);
       memberId = decoded.memberId;
     } catch (err) {
       // Token invalid, continue as non-member