Enable the clippy::pedantic lint group (#8429)

Instead of opting in to pedantic lints one by one, enable the whole
group and opt out of the noisy ones.

64% of the pedantic lints were already listed individually. This deletes
90 explicit lint lines, enables 51 pedantic lints we never listed, and
picks up new pedantic lints for free. Each opt-out carries its hit
count, so the cost of turning one back on is visible.

`restriction` and `nursery` stay opt-in per lint.

Stacked on top of #8430, which fixes the one real bug the new lints
found.

* [x] I have followed the instructions in the PR template

---------

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

crates/epaint/src/tessellator.rs

@@ -1519,11 +1519,11 @@ impl Tessellator {
 
                     if stroke.is_empty() {
                         return; // we are done
-                    } else {
-                        // we still need to do the stroke
-                        fill = Color32::TRANSPARENT; // don't fill again below
-                        break;
                     }
+
+                    // we still need to do the stroke
+                    fill = Color32::TRANSPARENT; // don't fill again below
+                    break;
                 }
             }
         }