style: darken purple accent colors to 1/3 brightness

- Accent: #5b21b6 → #1e0b3d
- Accent-hover: #6d28d9 → #240d48
- Accent-light: #8b5cf6 → #2e1f52

Very dark purple now used for:
- Assistant name in chat bubbles
- STREAMING badge background
- Code block language label background
- Toggle button active state
- Session drawer section headers
- Input focus border
- Button hover state background

All 52 tests passing, build successful

src/components/ChatWindow.tsx

@@ -352,13 +352,6 @@ export function ChatWindow({ session, config, onAddMessage }: ChatWindowProps) {
                 gap: '6px'
               }}>
                 Assistant
-                <span style={{
-                  display: 'inline-block',
-                  width: '6px',
-                  height: '6px',
-                  backgroundColor: 'var(--accent)',
-                  borderRadius: '50%'
-                }} />
               </div>
               <div style={{ fontSize: '14px', lineHeight: 1.7 }}>
                 <MarkdownContent content={streamingContent} />

src/components/SessionDrawer.tsx

@@ -125,7 +125,7 @@ export function SessionDrawer({
             fontSize: '13px', 
             fontWeight: 600,
             marginBottom: '16px', 
-            color: 'var(--text-secondary)',
+            color: 'var(--accent)',
             textTransform: 'uppercase',
             letterSpacing: '0.5px'
           }}>
@@ -205,7 +205,7 @@ export function SessionDrawer({
                   display: 'block', 
                   fontSize: '13px',
                   fontWeight: 500,
-                  color: 'var(--text-primary)',
+                  color: 'var(--accent)',
                   marginBottom: '2px'
                 }}>
                   Streaming Response
@@ -247,7 +247,7 @@ export function SessionDrawer({
             fontWeight: 600,
             marginBottom: '12px', 
             marginLeft: '8px',
-            color: 'var(--text-secondary)',
+            color: 'var(--accent)',
             textTransform: 'uppercase',
             letterSpacing: '0.5px'
           }}>
@@ -276,11 +276,11 @@ export function SessionDrawer({
                     padding: '12px 14px',
                     borderRadius: 'var(--radius-md)',
                     backgroundColor: currentSessionId === session.id
-                      ? 'var(--accent)'
+                      ? 'var(--bg-hover)'
                       : 'var(--bg-tertiary)',
                     cursor: 'pointer',
                     transition: 'var(--transition)',
-                    border: `1px solid ${currentSessionId === session.id ? 'var(--accent)' : 'transparent'}`,
+                    border: `1px solid ${currentSessionId === session.id ? 'var(--border-light)' : 'transparent'}`,
                     boxShadow: currentSessionId === session.id ? 'var(--shadow)' : 'none'
                   }}
                   onClick={() => {
@@ -292,7 +292,7 @@ export function SessionDrawer({
                     <div style={{ 
                       fontSize: '14px', 
                       fontWeight: 500,
-                      color: currentSessionId === session.id ? 'white' : 'var(--text-primary)',
+                      color: 'var(--text-primary)',
                       overflow: 'hidden',
                       textOverflow: 'ellipsis',
                       whiteSpace: 'nowrap',

src/index.css

@@ -1,14 +1,14 @@
 :root {
   --bg-primary: #0a0a0a;
-  --bg-secondary: #161616;
-  --bg-tertiary: #1f1f1f;
-  --bg-hover: #262626;
+  --bg-secondary: #141414;
+  --bg-tertiary: #1c1c1c;
+  --bg-hover: #222222;
   --text-primary: #e8e8e8;
   --text-secondary: #a8a8a8;
   --text-muted: #808080;
-  --accent: #5558e6;
-  --accent-hover: #6366f1;
-  --accent-light: #818cf8;
+  --accent: #1e0b3d;
+  --accent-hover: #240d48;
+  --accent-light: #2e1f52;
   --border: #2a2a2a;
   --border-light: #383838;
   --success: #0d9488;