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/package.json

@@ -6,11 +6,16 @@
   "scripts": {
     "dev": "vite",
     "build": "tsc && vite build",
-    "preview": "vite preview"
+    "preview": "vite preview",
+    "typecheck": "tsc --noEmit",
+    "test": "vitest run",
+    "test:watch": "vitest"
   },
   "dependencies": {
     "@hookform/resolvers": "^3.9.1",
+    "@tanstack/react-query": "^5.62.0",
     "axios": "^1.7.9",
+    "cmdk": "^1.0.4",
     "date-fns": "^3.6.0",
     "lucide-react": "^0.468.0",
     "react": "^18.3.1",
@@ -19,16 +24,23 @@
     "react-markdown": "^9.0.1",
     "react-router-dom": "^6.28.0",
     "remark-gfm": "^4.0.0",
+    "sonner": "^1.7.1",
     "zod": "^3.23.8"
   },
   "devDependencies": {
+    "@tanstack/react-query-devtools": "^5.62.0",
+    "@testing-library/jest-dom": "^6.6.3",
+    "@testing-library/react": "^16.1.0",
+    "@testing-library/user-event": "^14.5.2",
     "@types/react": "^18.3.12",
     "@types/react-dom": "^18.3.1",
     "@vitejs/plugin-react": "^4.3.4",
     "autoprefixer": "^10.4.20",
+    "jsdom": "^25.0.1",
     "postcss": "^8.4.49",
     "tailwindcss": "^3.4.16",
     "typescript": "^5.7.2",
-    "vite": "^6.0.5"
+    "vite": "^6.0.5",
+    "vitest": "^2.1.8"
   }
 }