fix(release): dispatch publish via exec successCmd not step output

The prior pattern relying on steps.semantic-release.outputs did not
fire. Move the publish dispatch into @semantic-release/exec successCmd,
which runs only after a release is actually published and has
nextRelease.version available. Also add GH_TOKEN env for gh CLI
(GITHUB_TOKEN alone is not read by gh).

.releaserc.json

@@ -5,7 +5,8 @@
     "@semantic-release/release-notes-generator",
     "@semantic-release/changelog",
     ["@semantic-release/exec", {
-      "prepareCmd": "sed -i 's/^version = \\\"[^\\\"]*\\\"/version = \\\"${nextRelease.version}\\\"/' Cargo.toml && cargo check"
+      "prepareCmd": "sed -i 's/^version = \\\"[^\\\"]*\\\"/version = \\\"${nextRelease.version}\\\"/' Cargo.toml && cargo check",
+      "successCmd": "echo \"::notice::release ${nextRelease.version} published; dispatching crate publish\" && gh workflow run publish.yml --ref main -f tag=v${nextRelease.version}"
     }],
     ["@semantic-release/git", {
       "assets": ["Cargo.toml", "Cargo.lock", "CHANGELOG.md"],