nix: name the crane derivations, instead of "cargo-package"

The root manifest is a pure [workspace], so crane finds no [package].name
to name its derivations after and falls back to a placeholder — every
build of crabidy logged two "crane will use a placeholder value" warnings
and produced cargo-package-0.1.0.drv, which says nothing about what was
built.

Name it in [workspace.metadata.crane], the spelling crane itself
suggests. Cargo ignores unknown workspace metadata, so this is a build
label and nothing more.

The cross build takes its name from the same root, which would leave the
native and aarch64 derivations both called crabidy-0.1.0; give it an
explicit pname so a build log can tell them apart.

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

Cargo.toml

@@ -22,6 +22,12 @@ members = [
 version = "0.1.0"
 edition = "2021"
 
+# This root manifest is a pure workspace, so crane finds no `[package].name` to
+# name its derivations after and warns that it is using a placeholder
+# ("cargo-package-0.1.0.drv" in the build log). Name it here instead.
+[workspace.metadata.crane]
+name = "crabidy"
+
 [workspace.dependencies]
 anyhow = "1"
 argon2 = { version = "0.5", features = ["std"] }

flake.nix

@@ -201,6 +201,10 @@
         crossArgs = {
           inherit src;
           strictDeps = true;
+          # Both builds take their name from the workspace root, so name this
+          # one for its target — otherwise the native and cross derivations are
+          # both "crabidy-0.1.0" and a build log cannot tell them apart.
+          pname = "crabidy-server-aarch64";
           # web-ui is a default feature; keep it on so the embedded UI ships.
           cargoExtraArgs = "--locked -p crabidy-server";
           CARGO_BUILD_TARGET = muslTarget;