Resolve clippy warnings in this round's changes

Three nits clippy flagged on the round 13 + 14 commits. Fix each:
* `RangeInclusive::contains` for the sidebar reveal-threshold guard.
* Reword the popover-anchor doc-comments so the `+ tile` lines don't
  get parsed as Markdown list items.
* Collapse the `if let Some(text)` + nested `if` in the external web
  keyboard handler into a single `let-and-and` chain.

No behavior change. cargo clippy -p ely_app: clean.
cargo test --workspace: 440 passed, 0 failed.

crates/ely_app/src/shell/web_surface_keyboard.rs

@@ -21,10 +21,10 @@ impl ElyShell {
             return;
         }
 
-        if let Some(text) = special_key_text(event) {
-            if self.type_text_in_external_web_viewport(tab_id, requested_url, text, cx) {
-                cx.stop_propagation();
-            }
+        if let Some(text) = special_key_text(event)
+            && self.type_text_in_external_web_viewport(tab_id, requested_url, text, cx)
+        {
+            cx.stop_propagation();
         }
     }