ci(dependabot): fix cargo workspace updates and refresh lockfiles (#629)

* ci(dependabot): fix cargo workspace updates and refresh lockfiles

Remove nested Cargo workspace members from Dependabot's cargo directories to avoid manifest resolution failures during grouped updates.

Add a Dependabot-only workflow that refreshes affected Cargo lockfiles, including the no_std target-specific resolution path, so CI can continue enforcing --locked and --frozen builds.

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

* ci(dependabot): address workflow review comments

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

* ci(dependabot): address workflow permission and toolchain comments

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

* ci(dependabot): stage no-std lockfile refresh

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

* ci(dependabot): harden refresh workflow

* ci(dependabot): refine workflow gating and staging

* ci(dependabot): harden workflow git operations

---------

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

.github/workflows/dependabot-refresh-cargo-lockfiles.yml

@@ -0,0 +1,129 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+#
+name: dependabot/refresh-cargo-lockfiles
+
+on:
+  pull_request_target:
+    types: [opened, synchronize, reopened]
+    branches: ["main"]
+
+concurrency:
+  group: dependabot-refresh-cargo-lockfiles-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  refresh-cargo-lockfiles:
+    permissions:
+      contents: write
+    if: >-
+      github.event.pull_request.user.login == 'dependabot[bot]' &&
+      github.event.pull_request.head.repo.full_name == github.repository
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd
+        with:
+          repository: ${{ github.event.pull_request.head.repo.full_name }}
+          ref: ${{ github.event.pull_request.head.ref }}
+          fetch-depth: 0
+          persist-credentials: false
+
+      - name: Setup Rust toolchain
+        run: |
+          rustup toolchain install 1.92.0 --profile minimal
+          rustup override set 1.92.0
+          cargo --version
+          rustc --version
+
+      - name: Refresh affected Cargo lockfiles
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          base_sha="${{ github.event.pull_request.base.sha }}"
+          head_sha="${{ github.event.pull_request.head.sha }}"
+
+          mapfile -t changed_files < <(git diff --name-only "$base_sha" "$head_sha" -- ':(glob)**/Cargo.toml' ':(glob)**/Cargo.lock')
+
+          if [ "${#changed_files[@]}" -eq 0 ]; then
+            echo "No Cargo manifest or lockfile changes detected."
+            exit 0
+          fi
+
+          declare -A manifests=()
+          for path in "${changed_files[@]}"; do
+            case "$path" in
+              bindings/ffi/*)
+                manifests["bindings/ffi/Cargo.toml"]=1
+                ;;
+              bindings/java/*)
+                manifests["bindings/java/Cargo.toml"]=1
+                ;;
+              bindings/python/*)
+                manifests["bindings/python/Cargo.toml"]=1
+                ;;
+              bindings/ruby/*)
+                manifests["bindings/ruby/Cargo.toml"]=1
+                ;;
+              bindings/wasm/*)
+                manifests["bindings/wasm/Cargo.toml"]=1
+                ;;
+              *)
+                manifests["Cargo.toml"]=1
+                ;;
+            esac
+          done
+
+          for manifest in "${!manifests[@]}"; do
+            echo "Refreshing lockfile for $manifest"
+            cargo metadata \
+              --config build.rustc="rustc" \
+              --config build.rustc-wrapper="" \
+              --config build.rustc-workspace-wrapper="" \
+              --format-version 1 \
+              --all-features \
+              --manifest-path "$manifest" > /dev/null
+          done
+
+          if [[ -n "${manifests[Cargo.toml]+x}" ]]; then
+            echo "Refreshing lockfile for tests/ensure_no_std/Cargo.toml (thumbv7m-none-eabi)"
+            cargo metadata \
+              --config build.rustc="rustc" \
+              --config build.rustc-wrapper="" \
+              --config build.rustc-workspace-wrapper="" \
+              --format-version 1 \
+              --manifest-path tests/ensure_no_std/Cargo.toml \
+              --filter-platform thumbv7m-none-eabi > /dev/null
+          fi
+
+      - name: Commit lockfile refresh
+        shell: bash
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          set -euo pipefail
+
+          mapfile -t lockfiles < <(git ls-files -m -o --exclude-standard -- ':(glob)**/Cargo.lock')
+
+          for lockfile in "${lockfiles[@]}"; do
+            git add "$lockfile"
+          done
+
+          if git diff --cached --quiet; then
+            echo "No Cargo lockfile changes required."
+            exit 0
+          fi
+
+          auth_header=$(printf 'x-access-token:%s' "$GH_TOKEN" | base64 | tr -d '\n')
+          trap 'git config --unset-all http.https://github.com/.extraheader' EXIT
+          git config http.https://github.com/.extraheader "AUTHORIZATION: basic ${auth_header}"
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git commit -m "build(deps): refresh Cargo lockfiles"
+          git push origin HEAD:${{ github.event.pull_request.head.ref }}