fix(diagnostics): bound formatting and release ingress before callbacks

Bound UTF-8 formatting and release diagnostic ingress before invoking
callbacks. Check error-ID collisions at Rust/C++ release final link.

Validation: diagnostic tests, strict Clippy, Miri and final-link cases.

flake.nix

@@ -22,6 +22,7 @@
           default = pkgs.mkShell {
             packages = [
               pkgs.rustup
+              pkgs.gcc
               pkgs.dfu-util
               pkgs.mdbook
               pkgs.ripgrep