feat: Add post image headers to /assets/header/

- Add SVG icons for external sites
    - Add polished logo to login
    - Update front matter in <blog>.md files

src/components/LoginComponent.jsx

@@ -36,10 +36,10 @@ const LoginComponent = ({ onLogin }) => {
                 </div>
                 <div>
                     <Label htmlFor="password">Password: </Label>
-                    <Input style={{ border: '1px solid #edbd7d' }} type="password" id="password" value={password} onChange={(e) => setPassword(e.target.value)} autoComplete="current-password" />
+                    <Input style={{ border: '1px solid #edbd7d', marginBottom: '10px' }} type="password" id="password" value={password} onChange={(e) => setPassword(e.target.value)} autoComplete="current-password" />
                 </div>
                 
-                <Button look="flat" type="submit">Login</Button>
+                <Button look="flat" type="submit" style={{ padding: '0 20px' }}>Login</Button>
                 <div>
                     <NotificationGroup style={{ textAlign: 'center' }}>
                     {error && (<Notification type={{ style: 'error', icon: true }} closeable={true} onClose={() => setError('')}>