ci: add release-crates workflow for crates.io publishing (#74)

Add automated crates.io publishing workflow using release-plz.

**New files:**
- \.github/workflows/release-crates.yml\ — Two-job workflow (open
release PR + publish crates)
- \ elease-plz.toml\ — Configuration with \git_release_enable = false\,
semver checks, conventional commit filtering

**Prerequisites for DevOps:**
1. Create \cratesio-publish\ GitHub environment
2. Configure trusted publishing on crates.io for \cadeau\ and \xmf-sys\
crates
3. Ensure \DEVOLUTIONSBOT_WRITE_TOKEN\ secret is available in this repo

Author: mamoreau-devolutions

.github/workflows/release-crates.yml

@@ -0,0 +1,62 @@
+name: Release crates
+
+permissions:
+  pull-requests: write
+  contents: write
+
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - master
+
+jobs:
+  # Create a PR with the new versions and changelog, preparing the next release.
+  open-pr:
+    name: Open release PR
+    environment: cratesio-publish
+    runs-on: ubuntu-latest
+    concurrency:
+      group: release-plz-${{ github.ref }}
+      cancel-in-progress: false
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 512
+
+      - name: Run release-plz
+        id: release-plz
+        uses: Devolutions/actions-public/release-plz@v1
+        with:
+          command: release-pr
+          manifest-path: rust/Cargo.toml
+          git-name: Devolutions Bot
+          git-email: bot@devolutions.net
+          github-token: ${{ secrets.DEVOLUTIONSBOT_WRITE_TOKEN }}
+
+  # Release unpublished packages.
+  release:
+    name: Release crates
+    environment: cratesio-publish
+    runs-on: ubuntu-latest
+    permissions:
+      id-token: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 512
+
+      - name: Authenticate with crates.io
+        id: auth
+        uses: rust-lang/crates-io-auth-action@v1
+
+      - name: Run release-plz
+        uses: Devolutions/actions-public/release-plz@v1
+        with:
+          command: release
+          manifest-path: rust/Cargo.toml
+          registry-token: ${{ steps.auth.outputs.token }}

release-plz.toml

@@ -0,0 +1,6 @@
+[workspace]
+git_release_enable = false
+semver_check = true
+pr_branch_prefix = "release-plz/"
+pr_name = "chore(release): prepare for publishing"
+release_commits = "^(feat|docs|fix|build|perf)"