Support multiple chat sessions within the web UI (#638)

* Enable support for multiple chat sessions within the web client

- Allow users to create multiple chat sessions and manage them
- Give chat session slugs based on the most recent message
- Update web UI to have a collapsible menu with active chats
- Move chat routes into a separate file

* Make the collapsible side panel more graceful, improve some styling elements of the new layout

* Support modification of the conversation title

- Add a new field to the conversation object
- Update UI to add a threedotmenu to each conversation

* Get the default conversation if a matching one is not found by id

src/interface/desktop/assets/khoj.css

@@ -107,7 +107,7 @@ a.khoj-nav-selected {
     background-color: var(--primary);
 }
 img.khoj-logo {
-    width: min(60vw, 111px);
+    width: min(60vw, 90px);
     max-width: 100%;
     justify-self: center;
 }
@@ -117,7 +117,7 @@ img.khoj-logo {
         display: grid;
         grid-auto-flow: column;
         gap: 20px;
-        padding: 16px 10px;
+        padding: 12px 10px;
         margin: 0 0 16px 0;
     }