Design overhaul: Dark fitness theme, no emojis

CSS:
- Dark background (#0a0a0f, #0d0d12, #15151b)
- Orange accent (#ff6b35)
- Muted text (#a1a1aa, #71717a)
- Inter font from Google Fonts
- Workout type colors (push/pull/legs/etc)

Dashboard:
- Calendar dots are CSS circles, not emoji
- Coach avatar uses SVG icon
- All emojis replaced with Icons.jsx SVGs
- Navigation uses proper icons

WorkoutPage:
- Warmup exercises without emojis
- Check icons instead of emoji checkmarks
- Arrow icons for navigation
- Fire icon for warmup section

Professional fitness app aesthetic inspired by Nike/FITBOD

frontend/src/App.css

@@ -461,15 +461,15 @@
 }
 
 .coach-avatar {
-  font-size: 2.5rem;
-  width: 60px;
-  height: 60px;
-  background: rgba(255,255,255,0.2);
+  width: 52px;
+  height: 52px;
+  background: rgba(255,255,255,0.15);
   border-radius: 50%;
   display: flex;
   align-items: center;
   justify-content: center;
   flex-shrink: 0;
+  color: rgba(255,255,255,0.9);
 }
 
 .coach-message {
@@ -549,13 +549,6 @@
   color: white;
 }
 
-.calendar-day.has-workout .day-dot {
-  color: var(--success);
-}
-
-.calendar-day.today .day-dot {
-  color: white;
-}
 
 .day-name {
   font-size: 0.7rem;
@@ -574,10 +567,17 @@
 }
 
 .day-dot {
-  font-size: 0.5rem;
+  width: 4px;
+  height: 4px;
+  border-radius: 50%;
+  background: var(--success);
   margin-top: 0.25rem;
 }
 
+.calendar-day.today .day-dot {
+  background: rgba(255,255,255,0.8);
+}
+
 /* Today's Workout */
 .todays-workout {
   display: flex;
@@ -731,6 +731,19 @@
   text-transform: uppercase;
 }
 
+.stat-icon {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+}
+
+/* Brand title with icon */
+.brand-title {
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+}
+
 /* Upcoming Workouts */
 .upcoming-workouts h2 {
   font-size: 1.1rem;
@@ -818,6 +831,9 @@
   font-size: 1rem;
   cursor: pointer;
   padding: 0.5rem;
+  display: flex;
+  align-items: center;
+  gap: 0.25rem;
 }
 
 /* Page Main */
@@ -1242,7 +1258,9 @@
 }
 
 .warmup-icon {
-  font-size: 1.5rem;
+  display: flex;
+  align-items: center;
+  color: var(--accent);
 }
 
 .warmup-title h2 {
@@ -1260,7 +1278,8 @@
 }
 
 .expand-icon {
-  font-size: 0.75rem;
+  display: flex;
+  align-items: center;
   color: var(--text-muted);
   transition: transform 0.2s;
 }
@@ -1362,6 +1381,10 @@
   font-size: 0.95rem;
   cursor: pointer;
   transition: all 0.2s;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 0.5rem;
 }
 
 .warmup-done-btn:hover {
@@ -1573,6 +1596,9 @@
 }
 
 .tip-badge {
+  display: flex;
+  align-items: center;
+  gap: 0.4rem;
   background: var(--bg-secondary);
   border: 1px solid var(--border);
   padding: 0.5rem 0.75rem;