feat: Improve UI navigation and logo visibility

- Update navigation labels: 'Navigation' → 'Ponderants', 'Edit Node' → 'Manual', 'Conversation' → 'Convo', 'Galaxy View' → 'Galaxy'
- Improve logo visibility with CSS transform scale(3.5) and higher contrast colors (#E0E0E0, #909296)
- Make logo square (viewBox 60x60) for better favicon display
- Enhance mobile UX with vertical navigation buttons and text labels
- Add 'Profile' label to user menu in navigation
- Improve sidebar highlighting with blue color, bold font, and rounded corners
- Fix layout issues: adjust chat padding for sidebar (260px) and bottom bar (90px)
- Make borders more subtle (#373A40 instead of #dee2e6)
- Increase sidebar width to 260px to accommodate logo and text
- Remove desktop top bar for cleaner layout
- Use IconChartBubbleFilled for galaxy navigation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

components/Navigation/MobileHeader.tsx

@@ -6,13 +6,13 @@
  * Fixed header for mobile devices showing the Ponderants logo.
  */
 
-import { Group, Image, Text, Paper } from '@mantine/core';
+import { Group, Image, Text, Paper, Box } from '@mantine/core';
 
 export function MobileHeader() {
   return (
     <Paper
       withBorder
-      p="md"
+      p="sm"
       radius={0}
       style={{
         position: 'fixed',
@@ -20,18 +20,18 @@ export function MobileHeader() {
         left: 0,
         right: 0,
         zIndex: 100,
-        borderBottom: '1px solid #dee2e6',
+        borderBottom: '1px solid #373A40',
       }}
     >
       <Group gap="sm" align="center">
-        <Image
-          src="/logo.svg"
-          alt="Ponderants logo"
-          w={56}
-          h={56}
-          style={{ flexShrink: 0 }}
-        />
-        <Text fw={700} size="xl">
+        <Box w={32} h={32} style={{ flexShrink: 0, display: 'flex', alignItems: 'center', justifyContent: 'center' }}>
+          <Image
+            src="/logo.svg"
+            alt="Ponderants logo"
+            style={{ width: '100%', height: '100%', transform: 'scale(3.5)' }}
+          />
+        </Box>
+        <Text fw={700} size="lg">
           Ponderants
         </Text>
       </Group>