Create initial pre-commit configuration

The commit introduces a basic `pre-commit` configuration
with hooks for auto-fixing common code quality issues:

* Ensure files end with a newline (`end-of-file-fixer`),
* Standardizing line endings to LF (`mixed-line-ending`), and
* Removing trailing whitespace (`trailing-whitespace`).

Use a home-brewed pre-commit CI action, because the organization
cannot install the necessary pre-commit GitHub application.

Draw inspiration from:
* https://github.com/isaak654/sandboxie-docs/blob/6169c206fa9978641dafddf34303404604beaf33/.pre-commit-config.yaml
* https://github.com/isaak654/sandboxie-docs/blob/84751989d8fdee890520f116ea9e2ab0ff9f9b53/.github/workflows/action.yml#L59-L87

Signed-off-by: Stavros Ntentos <[email protected]>

.github/workflows/pre-commit.yml

@@ -0,0 +1,34 @@
+name: pre-commit
+
+on:
+  # Triggers the workflow on ALL push or pull request events
+  # except for the `gh-pages`` branch
+  push:
+    branches-ignore:
+     - gh-pages
+  pull_request:
+    branches-ignore:
+     - gh-pages
+
+permissions:
+  contents: write
+
+jobs:
+  pre-commit:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - uses: actions/setup-python@v5
+      with:
+        python-version: 3.x
+
+    - uses: pre-commit/[email protected]
+
+    - name: Commit changes
+      if: ${{ !cancelled() && failure() }}
+      shell: bash
+      run: |
+        git config --local user.name "pre-commit-ci[bot]"
+        git config --local user.email "66853113+pre-commit-ci[bot]@users.noreply.github.com"
+        git commit -m "[pre-commit.ci] auto-fixes from pre-commit hooks" -a
+        git push origin HEAD:${{ github.head_ref || github.ref_name }}

.pre-commit-config.yaml

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+ci:
+  autofix_commit_msg: '[pre-commit.ci] auto-fixes from pre-commit hooks'
+
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.6.0
+    hooks:
+    - id: check-added-large-files
+      args:
+       - --maxkb=10000
+    - id: check-merge-conflict
+    - id: mixed-line-ending
+      args:
+       - --fix=lf
+    - id: detect-private-key
+    - id: end-of-file-fixer
+    - id: forbid-new-submodules
+    - id: trailing-whitespace