Add Zod validation to all API endpoints and remove debug test route

Adds schema-based input validation across helcim, events, members,
series, admin, and updates API endpoints. Removes the peer-support
debug test endpoint. Adds validation test coverage.

server/api/admin/members.post.js

@@ -6,15 +6,7 @@ export default defineEventHandler(async (event) => {
   try {
     await requireAdmin(event)
 
-    const body = await readBody(event)
-
-    // Validate required fields
-    if (!body.name || !body.email || !body.circle || !body.contributionTier) {
-      throw createError({
-        statusCode: 400,
-        statusMessage: 'Missing required fields'
-      })
-    }
+    const body = await validateBody(event, adminMemberCreateSchema)
 
     await connectDB()