Add ESLint + Prettier + EditorConfig tooling at repo root

v1.0 Phase 1.1 — repo-wide lint/format baseline.

- eslint.config.mjs (flat config) lints server, client, shared
- .prettierrc.json, .prettierignore, .editorconfig, .nvmrc
- Root package.json holds shared devDeps; per-package scripts keep
  their typecheck + test runners
- Fix 7 lint issues surfaced by the baseline run:
  - TicketDetail.tsx: replace ternary-with-side-effects with if/else
  - admin/Users.tsx: escape apostrophe in JSX
  - errorHandler.ts: typed err as unknown with ErrorLike refinement
  - users.ts: Prisma.UserUpdateInput instead of Record<string, any>
  - seed.ts: drop unused goddard binding
- Run prettier across tracked sources for a clean formatting baseline

client/vite.config.ts

@@ -1,5 +1,5 @@
-import { defineConfig } from 'vite'
-import react from '@vitejs/plugin-react'
+import { defineConfig } from 'vite';
+import react from '@vitejs/plugin-react';
 
 export default defineConfig({
   plugins: [react()],
@@ -8,4 +8,4 @@ export default defineConfig({
       '/api': 'http://localhost:3000',
     },
   },
-})
+});