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/render.rs

@@ -236,7 +236,7 @@ impl ElyShell {
             return;
         }
 
-        if cursor_x >= REVEAL_THRESHOLD_PX && cursor_x <= COLLAPSE_THRESHOLD_PX {
+        if (REVEAL_THRESHOLD_PX..=COLLAPSE_THRESHOLD_PX).contains(&cursor_x) {
             return;
         }