pre-commit: run markdown-link-check, oxipng, prettier manually

The "manual" stage in pre-commit refers to a specific hook stage designed for hooks that are not intended to run automatically during a standard git commit operation. Instead, these hooks are meant to be triggered explicitly by a user, typically when performing a full repository scan or a specific check.

This speeds up the standard `pre-commit run --all-files` run by not running these two hooks.

Both hooks are time consuming

Can run the manual hooks with:

`pre-commit run --all-files --hook-stage manual`

Add pre-commit manual stage run on CI to keep full coverage

.github/workflows/lint.yml

@@ -25,6 +25,8 @@ jobs:
           key: pre-commit|${{ env.PY }}|${{ hashFiles('.pre-commit-config.yaml') }}
       - name: Run pre-commit
         run: pre-commit run --all-files
+      - name: Run manual pre-commit hooks
+        run: pre-commit run --all-files --hook-stage manual
   ls-lint:
     name: Run ls-lint
     runs-on: ubuntu-latest