Feat/links checker with notifications

.github/workflows/link_checker.yml

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+name: Discord 404 checker (cron + manual test)
+
+on:
+  schedule:
+    # Runs every 15 minutes (UTC). Change as needed.
+    - cron: "*/5 * * * *"
+  workflow_dispatch: {}
+
+jobs:
+  check-links:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Install deps (none for this script)
+        run: python -m pip install --upgrade pip
+
+      - name: Run script
+        env:
+          DISCORD_WEBHOOK_URL: ${{ secrets.DISCORD_WEBHOOK_URL }}
+          USER_ID: ${{ secrets.USER_ID }}
+        run: |
+          python -u scripts/link_checker.py

scripts/link_checker.py

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+import json
+import os
+import urllib.error
+import urllib.request
+from pathlib import Path
+
+from src.config.logger import get_logger
+
+log = get_logger(__name__)
+
+
+# sends relevant info to webhook
+def send_discord(webhook_url: str, content: list[str]):
+    payload = {"content": "\n".join(content)}
+    req = urllib.request.Request(
+        webhook_url,
+        data=json.dumps(payload).encode("utf-8"),
+        headers={"Content-Type": "application/json", "User-Agent": "link-checker/1.0"},
+        method="POST",
+    )
+    try:
+        with urllib.request.urlopen(req) as resp:
+            log.info("Discord status:", status=resp.status)
+            log.info(resp.read().decode("utf-8", errors="ignore"))
+    except urllib.error.HTTPError as e:
+        body = e.read().decode("utf-8", errors="ignore")
+        log.error("Discord HTTPError:", error=e.code, response_body=body)
+        raise
+
+
+# webhook for the discord channel
+webhook = os.environ["DISCORD_WEBHOOK_URL"]
+# user id of the user we want to ping
+user_id = os.environ["USER_ID"]
+
+# works only if this script is in /scripts
+REPO_ROOT = Path(__file__).resolve().parents[1]
+# replace with any list
+URL_LIST_PATH = REPO_ROOT / "data" / "webpages" / "test_list.json"
+
+failed_urls = []
+
+with open(URL_LIST_PATH) as f:
+    urls = json.load(f)
+
+for url in urls:
+    url_status = urllib.request.urlopen(url).getcode()
+    if url_status != 200:
+        failed_urls.append(f"FAILED URL: {url}")
+    # uncomment this if you want to try the functionality with any other statuscode (or none)
+    # failed_urls.append("FAILED URL: " + url)
+
+payload = failed_urls
+payload.insert(0, f"<@{user_id}>, these links are returning a 404! Check these links.")
+
+if failed_urls:
+    send_discord(webhook, payload)