ci: lock workflow actions through an actions.lock lockfile

Mutable action tags are a supply-chain risk: a moved tag runs different code
without a diff. Every workflow action is now pinned through
.github/workflows/actions.lock, and CI verifies the lockfile so an out-of-sync
or tampered one fails instead of running.

.github/workflows/actions.lock

@@ -0,0 +1,26 @@
+# This file is machine-generated by `gh actions-lock`.
+# Do not edit by hand; run `gh actions-lock` to update.
+# Docs: https://gh.io/actions-lockfile
+version: 'v0.0.3'
+workflows:
+    '.github/workflows/ci.yml': []
+    '.github/workflows/freebsd.yml': []
+    '.github/workflows/house-rules.yml': []
+    '.github/workflows/nix.yml': []
+    '.github/workflows/packaging-lint.yml':
+        - 'actions/checkout@v7.0.1'
+        - 'step-security/harden-runner@v2.22.4'
+    '.github/workflows/release.yml': []
+    '.github/workflows/sonarcloud.yml': []
+    '.github/workflows/windows-arm64.yml': []
+dependencies:
+    'actions/checkout@v7.0.1':
+        ref: 'v7.0.1'
+        commit: 'sha1-3d3c42e5aac5ba805825da76410c181273ba90b1'
+        owner_id: 44036562
+        repo_id: 197814629
+    'step-security/harden-runner@v2.22.4':
+        ref: 'v2.22.4'
+        commit: 'sha1-1d88384fd173af6ecb012dfd0264a306b711241a'
+        owner_id: 88700172
+        repo_id: 422287306

.github/workflows/packaging-lint.yml

@@ -28,10 +28,10 @@ jobs:
     runs-on: windows-latest
     steps:
       - name: Harden runner
-        uses: step-security/harden-runner@1d88384fd173af6ecb012dfd0264a306b711241a # v2.22.4
+        uses: step-security/harden-runner@v2.22.4
         with:
           egress-policy: audit
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@v7.0.1
         with:
           persist-credentials: false
       - name: Install the pinned packaging toolchain