Add Sphinx-Gallery caching and stabilize CI data cache keys

- Add gallery output caching in docs.yml keyed by examples/**/*.py hash,
  so unchanged examples are not re-executed on subsequent builds
- Replace github.run_id with stable v1 suffix in data cache keys across
  both docs.yml and install-tests.yml to avoid unnecessary cache churn
  (downloaded datasets don't change between runs)

Author: bruAristimunha

.github/workflows/docs.yml

@@ -43,17 +43,25 @@ jobs:
       - name: Test documentation code blocks
         run: pytest docs/ -v
 
-      - name: Create/Restore Data Caches mne and Nilearn
+      - name: Create/Restore Data Caches
         id: cache-data
         uses: actions/cache@v4
         with:
           path: |
             ~/mne_data
             ~/nilearn_data
-          key: ${{ runner.os }}-data-${{ github.run_id }}
+          key: ${{ runner.os }}-data-v1
           restore-keys: |
             ${{ runner.os }}-data
 
+      - name: Restore Sphinx-Gallery Cache
+        uses: actions/cache@v4
+        with:
+          path: docs/source/generated/
+          key: ${{ runner.os }}-gallery-${{ hashFiles('examples/**/*.py') }}
+          restore-keys: |
+            ${{ runner.os }}-gallery-
+
       - name: Build Docs
         run: make -C docs html
 

.github/workflows/install-tests.yml

@@ -49,7 +49,7 @@ jobs:
           path: |
             ~/mne_data
             ~/nilearn_data
-          key: ${{ runner.os }}-${{ matrix.python-version }}-data-${{ github.run_id }}
+          key: ${{ runner.os }}-${{ matrix.python-version }}-data-v1
           restore-keys: |
             ${{ runner.os }}-${{ matrix.python-version }}-data
 
@@ -103,7 +103,7 @@ jobs:
           path: |
             ~/mne_data
             ~/nilearn_data
-          key: ${{ runner.os }}-integration-data-${{ github.run_id }}
+          key: ${{ runner.os }}-integration-data-v1
           restore-keys: |
             ${{ runner.os }}-integration-data