Add pre-commit config with file checks and ruff hooks

Restore pre-commit configuration adapted for the Python stack: keep
generic file checks (large files, case conflict, merge conflict, yaml,
trailing whitespace, end-of-file-fixer) and add ruff for linting and
formatting in place of the old prettier/Astro hooks.

Author: nikoshell

.pre-commit-config.yaml

@@ -0,0 +1,20 @@
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v6.0.0
+    hooks:
+      - id: check-added-large-files
+        args: ["--maxkb", "5000"]
+      - id: check-case-conflict
+      - id: check-merge-conflict
+      - id: check-yaml
+      - id: end-of-file-fixer
+        exclude_types: ["svg"]
+      - id: trailing-whitespace
+        exclude_types: ["svg"]
+
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.11.12
+    hooks:
+      - id: ruff
+        args: ["--fix"]
+      - id: ruff-format