feat(01-input-ux-01): add WeightInput, RepsInput wrappers + stepper CSS

- WeightInput: wraps StepperInput with step=2.5, suffix=kg
- RepsInput: wraps StepperInput with step=1, no suffix
- App.css: appended stepper styles (.stepper-wrapper, .stepper-btn, etc.)
- Buttons min 44x44px touch targets, font-size 16px on input
- No existing CSS removed; block appended at end

frontend/src/App.css

@@ -50,8 +50,8 @@
 .week-selector button {
   background: var(--bg-card);
   color: var(--text-primary);
-  width: 36px;
-  height: 36px;
+  width: 44px;
+  height: 44px;
   border-radius: 8px;
   font-size: 1.1rem;
   transition: all 0.2s;
@@ -506,8 +506,8 @@
 .calendar-nav {
   background: var(--bg);
   border: 1px solid var(--border);
-  width: 32px;
-  height: 32px;
+  width: 44px;
+  height: 44px;
   border-radius: 8px;
   cursor: pointer;
   display: flex;
@@ -659,6 +659,7 @@
   font-weight: 600;
   cursor: pointer;
   transition: all 0.2s;
+  min-height: 44px;
 }
 
 .start-workout-btn:hover {
@@ -834,6 +835,7 @@
   display: flex;
   align-items: center;
   gap: 0.25rem;
+  min-height: 44px;
 }
 
 /* Page Main */
@@ -874,6 +876,7 @@
   cursor: pointer;
   font-size: 0.85rem;
   color: var(--text);
+  min-height: 44px;
 }
 
 /* Info Grid */
@@ -954,6 +957,7 @@
   border-radius: 8px;
   cursor: pointer;
   color: var(--text);
+  min-height: 44px;
 }
 
 .save-btn {
@@ -965,6 +969,7 @@
   border-radius: 8px;
   cursor: pointer;
   font-weight: 600;
+  min-height: 44px;
 }
 
 .save-btn:disabled {
@@ -1056,6 +1061,7 @@
   font-size: 0.9rem;
   color: var(--text-muted);
   transition: all 0.2s;
+  min-height: 44px;
 }
 
 .tab-btn.active {
@@ -1322,6 +1328,7 @@
   border-radius: 10px;
   cursor: pointer;
   transition: all 0.2s;
+  min-height: 44px;
 }
 
 .warmup-item:hover {
@@ -1385,6 +1392,7 @@
   align-items: center;
   justify-content: center;
   gap: 0.5rem;
+  min-height: 44px;
 }
 
 .warmup-done-btn:hover {
@@ -1433,6 +1441,7 @@
   cursor: pointer;
   transition: all 0.2s;
   margin-top: 1rem;
+  min-height: 44px;
 }
 
 .finish-workout-btn:hover {
@@ -1777,9 +1786,150 @@
   font-weight: 600;
   cursor: pointer;
   transition: all 0.2s;
+  min-height: 44px;
 }
 
 .start-btn:hover {
   background: var(--accent-hover);
   transform: scale(1.02);
 }
+
+/* ============================================
+   GLOBAL INPUT ACCESSIBILITY
+   Ensure all inputs have font-size >= 16px to prevent iOS auto-zoom
+   ============================================ */
+
+input[type="text"],
+input[type="email"],
+input[type="password"],
+input[type="number"],
+input[type="tel"],
+select,
+textarea {
+  font-size: 16px;
+}
+
+/* ============================================
+   STEPPER INPUT COMPONENT
+   ============================================ */
+
+.stepper-wrapper {
+  display: flex;
+  flex-direction: column;
+  gap: 0.4rem;
+  width: 100%;
+}
+
+.stepper-label {
+  font-size: 0.75rem;
+  color: var(--text-muted);
+  font-weight: 500;
+  text-transform: uppercase;
+  letter-spacing: 0.5px;
+}
+
+.stepper-container {
+  display: flex;
+  align-items: center;
+  gap: 0.25rem;
+  background: var(--bg-card);
+  border-radius: 8px;
+  border: 1px solid var(--border);
+  padding: 0.2rem;
+  height: 48px;
+}
+
+.stepper-btn {
+  width: 44px;
+  height: 44px;
+  min-width: 44px;
+  min-height: 44px;
+  background: var(--bg-secondary);
+  border: none;
+  border-radius: 6px;
+  color: var(--text-primary);
+  font-size: 1.4rem;
+  font-weight: 300;
+  cursor: pointer;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  transition: background 0.15s, color 0.15s;
+  flex-shrink: 0;
+  line-height: 1;
+}
+
+.stepper-btn:hover:not(:disabled) {
+  background: var(--accent);
+  color: white;
+}
+
+.stepper-btn:active:not(:disabled) {
+  transform: scale(0.94);
+}
+
+.stepper-btn:disabled {
+  opacity: 0.35;
+  cursor: not-allowed;
+}
+
+.stepper-input-wrapper {
+  flex: 1;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 0.25rem;
+  min-width: 0;
+}
+
+.stepper-input {
+  flex: 1;
+  min-width: 0;
+  background: transparent;
+  border: none;
+  color: var(--text-primary);
+  font-size: 16px; /* >= 16px prevents iOS auto-zoom */
+  font-weight: 600;
+  text-align: center;
+  padding: 0.4rem 0.25rem;
+  outline: none;
+  font-family: inherit;
+}
+
+.stepper-input:disabled {
+  opacity: 0.6;
+  cursor: not-allowed;
+}
+
+/* Remove browser native number spinners */
+.stepper-input::-webkit-outer-spin-button,
+.stepper-input::-webkit-inner-spin-button {
+  -webkit-appearance: none;
+  margin: 0;
+}
+
+.stepper-input[type='number'] {
+  -moz-appearance: textfield;
+}
+
+.input-suffix {
+  color: var(--text-muted);
+  font-size: 0.8rem;
+  font-weight: 500;
+  white-space: nowrap;
+  flex-shrink: 0;
+}
+
+/* Mobile: slightly larger touch targets */
+@media (max-width: 480px) {
+  .stepper-container {
+    height: 52px;
+  }
+
+  .stepper-btn {
+    width: 48px;
+    height: 48px;
+    min-width: 48px;
+    min-height: 48px;
+  }
+}