feat(ci): separate linkcheck to standalone workflow

The linkcheck is less and less reliable in past weeks. It seems that
some of the sites are broken often, it might be also caused by them
blocking GitHub ranges as such probing might be visible on some of them.

Separating the workflow allows us to execute it only on documentation
changes (we still want to run regular documentation build on all pull
requests to make it required).

.github/workflows/docs.yml

@@ -2,7 +2,7 @@
 #
 # SPDX-License-Identifier: GPL-3.0-or-later
 
-name: Docs
+name: Documentation
 
 on:
   push:
@@ -44,38 +44,3 @@ jobs:
       with:
         name: Documentation
         path: docs/_build/html
-
-  linkcheck:
-    runs-on: ubuntu-24.04
-    name: Linkcheck
-
-    steps:
-    - uses: actions/checkout@v4
-    - name: Set up Python
-      uses: actions/setup-python@v5
-      with:
-        python-version: '3.12'
-    - uses: astral-sh/setup-uv@v3
-    - name: Install apt dependencies
-      run: |
-        sudo apt update
-        sudo apt install -y graphviz
-    - name: Install Python dependencies
-      run: |
-        uv pip install --system -r docs/requirements.txt
-    - name: Sphinx linkcheck
-      run: |
-        ./ci/run-docs linkcheck
-    - name: Sphinx linkcheck collect
-      if: always()
-      run: |
-        echo "::add-matcher::.github/matchers/sphinx-linkcheck.json"
-        echo "::add-matcher::.github/matchers/sphinx-linkcheck-warn.json"
-        sed 's@^@docs/@' docs/_build/linkcheck/output.txt
-        echo "::remove-matcher owner=sphinx::"
-        echo "::remove-matcher owner=sphinx-warn::"
-    - uses: actions/upload-artifact@v4.4.0
-      if: always()
-      with:
-        name: Linkcheck report
-        path: docs/_build/linkcheck/output.txt

.github/workflows/linkcheck.yml

@@ -0,0 +1,58 @@
+# Copyright © Michal Čihař <michal@weblate.org>
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+name: Linkcheck
+
+on:
+  push:
+    paths:
+    - docs/**.rst
+    - docs/requirements.txt
+    - .github/workflows/linkcheck.yml
+  pull_request:
+    paths:
+    - docs/**.rst
+    - docs/requirements.txt
+    - .github/workflows/linkcheck.yml
+  schedule:
+  - cron: 30 5 * * *
+
+permissions:
+  contents: read
+
+jobs:
+  linkcheck:
+    runs-on: ubuntu-24.04
+    name: Linkcheck
+
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: '3.12'
+    - uses: astral-sh/setup-uv@v3
+    - name: Install apt dependencies
+      run: |
+        sudo apt update
+        sudo apt install -y graphviz
+    - name: Install Python dependencies
+      run: |
+        uv pip install --system -r docs/requirements.txt
+    - name: Sphinx linkcheck
+      run: |
+        ./ci/run-docs linkcheck
+    - name: Sphinx linkcheck collect
+      if: always()
+      run: |
+        echo "::add-matcher::.github/matchers/sphinx-linkcheck.json"
+        echo "::add-matcher::.github/matchers/sphinx-linkcheck-warn.json"
+        sed 's@^@docs/@' docs/_build/linkcheck/output.txt
+        echo "::remove-matcher owner=sphinx::"
+        echo "::remove-matcher owner=sphinx-warn::"
+    - uses: actions/upload-artifact@v4.4.0
+      if: always()
+      with:
+        name: Linkcheck report
+        path: docs/_build/linkcheck/output.txt