Add player setup form with validation and field error highlighting

- Dynamic name fields (3–6 players) with add/remove controls
- Start button disabled until all names are non-blank and unique;
  uniqueness check normalizes internal whitespace so "Bob  Smith"
  and "Bob Smith" are treated as the same name
- Names passed to game state are edge-trimmed only, preserving
  internal spacing as the user typed it
- Failing fields highlighted with red border and light red background
- PrimaryButton gains disabled prop with faded/flat appearance;
  active press state suppressed when disabled
- All round buttons now use consistent shadow and translateY values

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/PrimaryButton.module.css

@@ -11,7 +11,13 @@
   transition: transform 80ms ease, box-shadow 80ms ease;
 }
 
-.button:active {
+.button:active:not(:disabled) {
   transform: translateY(2px);
   box-shadow: 0 2px 6px rgba(0, 0, 0, 0.2);
 }
+
+.button:disabled {
+  opacity: 0.45;
+  box-shadow: none;
+  cursor: not-allowed;
+}

src/components/PrimaryButton.tsx

@@ -3,11 +3,12 @@ import styles from './PrimaryButton.module.css'
 interface Props {
   onClick: () => void
   children: React.ReactNode
+  disabled?: boolean
 }
 
-export default function PrimaryButton({ onClick, children }: Props) {
+export default function PrimaryButton({ onClick, children, disabled }: Props) {
   return (
-    <button className={styles.button} onClick={onClick}>
+    <button className={styles.button} onClick={onClick} disabled={disabled}>
       {children}
     </button>
   )

src/pages/PlayerSetup.module.css

@@ -0,0 +1,71 @@
+.row {
+  display: flex;
+  align-items: center;
+  gap: 0.75rem;
+  margin-bottom: 0.75rem;
+}
+
+.nameInput {
+  flex: 1;
+  padding: 0.85rem 1rem;
+  font-size: 1.1rem;
+  font-family: inherit;
+  border: 1.5px solid #c8b99a;
+  border-radius: 0.75rem;
+  background: #fdfaf4;
+}
+
+.nameInputError {
+  border-color: #c0392b;
+  background: #fff5f5;
+}
+
+.removeBtn {
+  flex-shrink: 0;
+  width: 2.5rem;
+  height: 2.5rem;
+  border-radius: 50%;
+  border: none;
+  background: #d94f4f;
+  color: white;
+  font-size: 1.25rem;
+  line-height: 1;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  cursor: pointer;
+  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.25);
+  transition: transform 80ms ease, box-shadow 80ms ease;
+}
+
+.removeBtn:active {
+  transform: translateY(2px);
+  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.2);
+}
+
+.addRow {
+  display: flex;
+  justify-content: center;
+  margin-top: 0.5rem;
+}
+
+.addBtn {
+  width: 3rem;
+  height: 3rem;
+  border-radius: 50%;
+  border: none;
+  background: #a8d5e8;
+  font-size: 1.75rem;
+  line-height: 1;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  cursor: pointer;
+  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.25);
+  transition: transform 80ms ease, box-shadow 80ms ease;
+}
+
+.addBtn:active {
+  transform: translateY(2px);
+  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.2);
+}

src/pages/PlayerSetup.tsx

@@ -1,14 +1,67 @@
+import { useState } from 'react'
 import PageFrame from '../components/PageFrame'
 import PrimaryButton from '../components/PrimaryButton'
+import styles from './PlayerSetup.module.css'
 
 interface Props {
-  onStart: () => void
+  onStart: (players: string[]) => void
+}
+
+function normalize(s: string) {
+  return s.trim().replace(/\s+/g, ' ')
 }
 
 export default function PlayerSetup({ onStart }: Props) {
+  const [names, setNames] = useState<string[]>(['', '', ''])
+
+  function updateName(i: number, value: string) {
+    setNames(n => n.map((v, idx) => (idx === i ? value : v)))
+  }
+
+  function addName() {
+    setNames(n => [...n, ''])
+  }
+
+  function removeName(i: number) {
+    setNames(n => n.filter((_, idx) => idx !== i))
+  }
+
+  const normalized = names.map(normalize)
+  const counts = new Map<string, number>()
+  normalized.forEach(n => counts.set(n, (counts.get(n) ?? 0) + 1))
+  const fieldErrors = normalized.map(n => n === '' || (counts.get(n) ?? 0) > 1)
+  const isValid = fieldErrors.every(e => !e)
+
   return (
-    <PageFrame title="Player Setup" footer={<PrimaryButton onClick={onStart}>Start</PrimaryButton>}>
-      {null}
+    <PageFrame
+      title="Player Setup"
+      footer={
+        <PrimaryButton onClick={() => onStart(names.map(n => n.trim()))} disabled={!isValid}>
+          Start
+        </PrimaryButton>
+      }
+    >
+      {names.map((name, i) => (
+        <div key={i} className={styles.row}>
+          <input
+            className={`${styles.nameInput}${fieldErrors[i] ? ` ${styles.nameInputError}` : ''}`}
+            type="text"
+            placeholder={`Player ${i + 1}`}
+            value={name}
+            onChange={e => updateName(i, e.target.value)}
+          />
+          {i >= 3 && (
+            <button className={styles.removeBtn} onClick={() => removeName(i)}>
+              ×
+            </button>
+          )}
+        </div>
+      ))}
+      {names.length < 6 && (
+        <div className={styles.addRow}>
+          <button className={styles.addBtn} onClick={addName}>+</button>
+        </div>
+      )}
     </PageFrame>
   )
 }