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/src/components/Avatar.tsx

@@ -1,14 +1,20 @@
 const PALETTE = [
-  '#ef4444', '#f97316', '#f59e0b', '#10b981',
-  '#06b6d4', '#3b82f6', '#8b5cf6', '#ec4899',
-]
+  '#ef4444',
+  '#f97316',
+  '#f59e0b',
+  '#10b981',
+  '#06b6d4',
+  '#3b82f6',
+  '#8b5cf6',
+  '#ec4899',
+];
 
 function nameToColor(name: string): string {
-  let hash = 0
+  let hash = 0;
   for (let i = 0; i < name.length; i++) {
-    hash = name.charCodeAt(i) + ((hash << 5) - hash)
+    hash = name.charCodeAt(i) + ((hash << 5) - hash);
   }
-  return PALETTE[Math.abs(hash) % PALETTE.length]
+  return PALETTE[Math.abs(hash) % PALETTE.length];
 }
 
 function initials(name: string): string {
@@ -17,18 +23,18 @@ function initials(name: string): string {
     .slice(0, 2)
     .map((n) => n[0])
     .join('')
-    .toUpperCase()
+    .toUpperCase();
 }
 
 const SIZES = {
   sm: 'w-6 h-6 text-xs',
   md: 'w-8 h-8 text-sm',
   lg: 'w-10 h-10 text-base',
-}
+};
 
 interface AvatarProps {
-  name: string
-  size?: keyof typeof SIZES
+  name: string;
+  size?: keyof typeof SIZES;
 }
 
 export default function Avatar({ name, size = 'md' }: AvatarProps) {
@@ -40,5 +46,5 @@ export default function Avatar({ name, size = 'md' }: AvatarProps) {
     >
       {initials(name)}
     </div>
-  )
+  );
 }