ci: add new link checker workflow for website (#8516)

Turns out we have several broken links on our website currently. Broken
links don't make a good impression so we should catch them as early as
possible.

Due to how our website is laid out, that isn't always possible to catch
these dead links in CI. The next best thing we can do is run a cron-job
in our CI that checks our sourcecode and makes sure all links (including
relative ones) are reachable.

---------

Signed-off-by: Thomas Eizinger <thomas@eizinger.io>

.github/workflows/website-links.yml

@@ -0,0 +1,34 @@
+name: Website Links
+
+on:
+  repository_dispatch:
+  workflow_dispatch:
+  schedule:
+    - cron: "00 18 * * *"
+
+defaults:
+  run:
+    working-directory: website # Specify working directory to ensure the `.lycheeignore` file is picked up.
+
+jobs:
+  linkChecker:
+    runs-on: ubuntu-latest
+    permissions:
+      issues: write # required for peter-evans/create-issue-from-file
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Check links on website
+        id: lychee
+        uses: lycheeverse/lychee-action@f613c4a64e50d792e0b31ec34bbcbba12263c6a6 # v2.3.0
+        with:
+          fail: false
+          args: --verbose --no-progress --exclude-all-private --base https://firezone.dev .
+
+      - name: Create Issue From File
+        if: steps.lychee.outputs.exit_code != 0
+        uses: peter-evans/create-issue-from-file@e8ef132d6df98ed982188e460ebb3b5d4ef3a9cd # v5.0.1
+        with:
+          title: Link Checker Report
+          content-filepath: ./lychee/out.md
+          labels: report, automated issue

website/.lycheeignore

@@ -0,0 +1,8 @@
+# Links included in our website known to not be broken but lychee can't check them :(
+
+https://www.gartner.com/en/information-technology/glossary/zero-trust-network-access-ztna-/
+https://portal.azure.com
+https://x.com/firezonehq
+https://admin.google.com/ac/owl
+https://www.flexjobs.com/blog/post/exploring-the-impact-of-remote-work-on-mental-health-and-the-workplace/
+.prettierrc.json