make item id optional as queued for database insert, rename item constructor, add comments

src/profile/history.rs

@@ -30,7 +30,7 @@ impl History {
     pub fn open(&self, request: GString, title: Option<GString>) {
         let mut memory = self.memory.borrow_mut();
         if !memory.open(&request) {
-            memory.add(Item::create(0, request, title)) // @TODO
+            memory.add(Item::init(request, title))
         }
     }
 

src/profile/history/item.rs

@@ -2,19 +2,27 @@ use gtk::glib::{DateTime, GString};
 
 #[derive(Clone)]
 pub struct Item {
-    pub id: i64,
+    /// Queued for DB insert on value is `None` (e.g. on app close)
+    pub id: Option<i64>,
+    /// The value for navigation request entry
     pub request: GString,
+    /// Some history items may contain title (e.g. gemtext documents and system tabs)
+    /// * used as the additional criteria for search in the navbar suggestions widget
     pub title: Option<GString>,
+    /// Collect opened count with event time
+    /// * used for sort order search results in the navbar suggestions widget
     pub opened: Vec<DateTime>,
+    /// Collect tab closed count with event time
+    /// * used in recently closed pages menu
     pub closed: Vec<DateTime>,
 }
 
 impl Item {
     // Constructors
 
-    pub fn create(id: i64, request: GString, title: Option<GString>) -> Self {
+    pub fn init(request: GString, title: Option<GString>) -> Self {
         Self {
-            id,
+            id: None,
             request,
             title,
             opened: vec![now()],