Add user information and calendar list to sidebar

Backend changes:
- Add /api/user/info endpoint to fetch user details and calendar list
- Create UserInfo and CalendarInfo models for API responses
- Filter out generic calendar collections from sidebar display
- Extract readable calendar names with proper title case formatting

Frontend changes:
- Fetch and display user info (username, server URL) in sidebar header
- Show list of user's calendars with hover effects and styling
- Add loading states and error handling for user info
- Reorganize sidebar layout: header, navigation, calendar list, logout

Styling:
- Enhanced sidebar with user info section and calendar list
- Responsive design hides user info and calendar list on mobile
- Improved logout button positioning in sidebar footer
- Professional styling with proper spacing and visual hierarchy

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

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

src/services/calendar_service.rs

@@ -25,6 +25,19 @@ impl Default for ReminderAction {
     }
 }
 
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
+pub struct UserInfo {
+    pub username: String,
+    pub server_url: String,
+    pub calendars: Vec<CalendarInfo>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
+pub struct CalendarInfo {
+    pub path: String,
+    pub display_name: String,
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
 pub struct CalendarEvent {
     pub uid: String,
@@ -135,6 +148,48 @@ impl CalendarService {
         Self { base_url }
     }
 
+    /// Fetch user info including available calendars
+    pub async fn fetch_user_info(&self, token: &str, password: &str) -> Result<UserInfo, String> {
+        let window = web_sys::window().ok_or("No global window exists")?;
+        
+        let opts = RequestInit::new();
+        opts.set_method("GET");
+        opts.set_mode(RequestMode::Cors);
+
+        let url = format!("{}/user/info", self.base_url);
+        let request = Request::new_with_str_and_init(&url, &opts)
+            .map_err(|e| format!("Request creation failed: {:?}", e))?;
+
+        request.headers().set("Authorization", &format!("Bearer {}", token))
+            .map_err(|e| format!("Authorization header setting failed: {:?}", e))?;
+        
+        request.headers().set("X-CalDAV-Password", password)
+            .map_err(|e| format!("Password header setting failed: {:?}", e))?;
+
+        let resp_value = JsFuture::from(window.fetch_with_request(&request))
+            .await
+            .map_err(|e| format!("Network request failed: {:?}", e))?;
+
+        let resp: Response = resp_value.dyn_into()
+            .map_err(|e| format!("Response cast failed: {:?}", e))?;
+
+        let text = JsFuture::from(resp.text()
+            .map_err(|e| format!("Text extraction failed: {:?}", e))?)
+            .await
+            .map_err(|e| format!("Text promise failed: {:?}", e))?;
+
+        let text_string = text.as_string()
+            .ok_or("Response text is not a string")?;
+
+        if resp.ok() {
+            let user_info: UserInfo = serde_json::from_str(&text_string)
+                .map_err(|e| format!("JSON parsing failed: {}", e))?;
+            Ok(user_info)
+        } else {
+            Err(format!("Request failed with status {}: {}", resp.status(), text_string))
+        }
+    }
+
     /// Fetch calendar events for a specific month
     pub async fn fetch_events_for_month(
         &self,