ci: guard docs drift — mkdocs --strict as a PR check + link/anchor validation (#149)

Adds the docs PR gate, the validation block, and pinned docs deps. Also adds the
previously-orphaned index.md to the nav (as Overview) so the omitted_files check
passes.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: lesnik512

.github/workflows/_checks.yml

@@ -16,6 +16,14 @@ jobs:
       - run: uv python pin 3.10
       - run: just install lint-ci
 
+  docs:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: extractions/setup-just@v4
+      - uses: astral-sh/setup-uv@v8.2.0
+      - run: just docs-build
+
   pytest:
     runs-on: ubuntu-latest
     strategy:

docs/requirements.txt

@@ -1,2 +1,2 @@
-mkdocs
-mkdocs-material
+mkdocs>=1.6,<2
+mkdocs-material>=9,<10

mkdocs.yml

@@ -4,6 +4,7 @@ repo_url: https://github.com/modern-python/lite-bootstrap
 docs_dir: docs
 edit_uri: edit/main/docs/
 nav:
+  - Overview: index.md
   - Introduction:
       - Quickstart: introduction/quickstart.md
       - Installation: introduction/installation.md
@@ -51,6 +52,12 @@ theme:
         icon: material/brightness-4
         name: Switch to system preference
 
+validation:
+  omitted_files: warn
+  absolute_links: warn
+  unrecognized_links: warn
+  anchors: warn
+
 markdown_extensions:
   - toc:
       permalink: true