docs(readme): use absolute URLs for logo images (#21)

* fix(clippy): address new lints from rust-1.95

Three new clippy errors started firing on `-D warnings` after the
rust-1.95 release:

- `clippy::manual_checked_ops` in src/catalog/builder.rs: rewrite
  the `pct` closure with `checked_div(total).unwrap_or(0)`, which
  is semantically identical to the existing `if total == 0 { 0 }
  else { (n * 100) / total }` form.
- `clippy::unnecessary_sort_by` in src/catalog/index.rs (x2):
  replace `sort_by(|a, b| b.1.cmp(&a.1))` with
  `sort_by_key(|b| std::cmp::Reverse(b.1))`. Both forms produce a
  stable sort by `.1` descending.

No behavioral change. Unblocks the pre-commit hook so README and
other commits can land again.

* docs(readme): use absolute URLs for logo images

Use https://raw.githubusercontent.com/<org>/<repo>/main/... for logo
references so they render on crates.io. Relative paths render correctly
on GitHub but are dropped by the crates.io README sanitizer, leaving a
broken image at the top of every crate page.

Author: nh13

README.md

@@ -13,9 +13,9 @@ Identify which human reference genome was used to align a BAM/SAM/CRAM file.
 <p>
 <a href="https://fulcrumgenomics.com">
 <picture>
-  <source media="(prefers-color-scheme: dark)" srcset=".github/logos/fulcrumgenomics-dark.svg">
-  <source media="(prefers-color-scheme: light)" srcset=".github/logos/fulcrumgenomics-light.svg">
-  <img alt="Fulcrum Genomics" src=".github/logos/fulcrumgenomics-light.svg" height="100">
+  <source media="(prefers-color-scheme: dark)" srcset="https://raw.githubusercontent.com/fulcrumgenomics/ref-solver/main/.github/logos/fulcrumgenomics-dark.svg">
+  <source media="(prefers-color-scheme: light)" srcset="https://raw.githubusercontent.com/fulcrumgenomics/ref-solver/main/.github/logos/fulcrumgenomics-light.svg">
+  <img alt="Fulcrum Genomics" src="https://raw.githubusercontent.com/fulcrumgenomics/ref-solver/main/.github/logos/fulcrumgenomics-light.svg" height="100">
 </picture>
 </a>
 </p>