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/shapes/bezier_shape.rs

@@ -1,5 +1,3 @@
-#![expect(clippy::many_single_char_names)]
-
 use core::ops::Range;
 
 use crate::{Color32, PathShape, PathStroke, Shape};