ci: upgrade lychee to v0.24.1 and fix broken link checks

lychee v0.24.1 (system binary) changed behavior: placeholder URLs like
scheme://hostname:port now raise a hard parse error instead of being
silently rewritten to file:// (which the old ignore pattern relied on).
The 30-day cache had been masking this and other pre-existing failures.

- Bump pre-commit lychee rev from v0.22.0 to v0.24.1
- Replace scheme://hostname:port placeholder URLs with concrete examples
  (http://proxy.example.com:8080) in both davclient.py and async_davclient.py
- Update .lycheeignore:
  - Widen example.com pattern to cover ports
  - Add domain/*, credentialed localhost, oxhost2 Docker hostname
  - Add Google API, fsf.org, oxpedia.org, httpd.apache.org, sphinx URL template
  - Remove stale comment about file:// rewriting (gone in 0.24.1)

prompt: git push -f github fails on lychee hook. How do I run the test?
  Why is it breaking just now? I want symmetry between both files.
  Also update pre-commit config to use 0.24.1.

AI Prompts:
claude-sonnet-4-6: `git push -f github` fails on the lychee hook in the pre-commit setup.  How do I run the test?  Why is it breaking just now, I can't see any recent changes causing this to break?
claude-sonnet-4-6: a55f9bb was added in january.  Why does this break only now?  I want symmetry, so the same fix should be applied to both files.  I also don't understand why the existing line in .lycheeignore works for the sync davclient but not for async_davclient
claude-sonnet-4-6: commit

Author: tobixen

.lycheeignore

@@ -1,10 +1,15 @@
 # Example domains that don't resolve
 https?://your\.server\.example\.com/.*
-https?://.*\.example\.com/.*
+https?://.*\.example\.com(:\d+)?(/.*)?$
+https?://domain/.*
 
 # Localhost URLs for test servers (not accessible in CI)
 http://localhost:\d+/.*
 http://localhost/.*
+http://.*@localhost:\d+/.*
+
+# Internal Docker hostnames (only reachable inside compose network)
+http://oxhost2:\d+/.*
 
 # CalDAV endpoints that require authentication (401/403 expected)
 https://caldav\.fastmail\.com/.*
@@ -24,8 +29,21 @@ http://nextcloud.org/ns
 http://owncloud.org/ns
 
 
+# Google API endpoints (require auth — 401/404/405 expected)
+https://apidata\.googleusercontent\.com/.*
+https://oauth2\.googleapis\.com/.*
+
+# Personal/demo test server (may be down)
+https?://davical\.bekkenstenveien53c\.oslo\.no/.*
+
+# Dead or broken links we can't fix
+http://fsf\.org/.*
+http://oxpedia\.org/.*
+http://httpd\.apache\.org/.*
+# GitHub URL template in sphinx conf (contains encoded braces, always 404)
+https://github\.com/python-caldav/caldav/blob/master/%7B.*
+
 # Other junk that was never meant to be followed
-# lychee converts unknown schemes to file:// URLs before matching ignore patterns
 file://.*/scheme:.*
 /17149682/.*
 http://x/

.pre-commit-config.yaml

@@ -32,7 +32,7 @@ repos:
         stages: [commit-msg]
 
   - repo: https://github.com/lycheeverse/lychee
-    rev: lychee-v0.22.0
+    rev: lychee-v0.24.1
     hooks:
       - id: lychee
         args: ["--no-progress", "--timeout", "10", "--exclude-path", ".lycheeignore", "--max-cache-age=30d", "--cache"]

caldav/async_davclient.py

@@ -124,7 +124,7 @@ def __init__(
 
         Args:
             url: CalDAV server URL, domain, or email address.
-            proxy: Proxy server (scheme://hostname:port).
+            proxy: Proxy server (e.g. http://proxy.example.com:8080).
             username: Username for authentication.
             password: Password for authentication.
             auth: Custom auth object (httpx.Auth or niquests AuthBase).

caldav/davclient.py

@@ -198,11 +198,11 @@ def __init__(
                - Full URL: `https://caldav.example.com/dav/`
                - Domain: `example.com` (will attempt RFC6764 discovery if enable_rfc6764=True)
                - Email: `user@example.com` (will attempt RFC6764 discovery if enable_rfc6764=True)
-               - URL with auth: `scheme://user:pass@hostname:port`
+               - URL with auth: `http://user:pass@proxy.example.com:8080`
                - Omit URL: Use `username='user@example.com'` for discovery
           username: Username for authentication. If url is omitted and username contains @,
                     RFC6764 discovery will be attempted using the username as email address.
-          proxy: A string defining a proxy server: `scheme://hostname:port`. Scheme defaults to http, port defaults to 8080.
+          proxy: A string defining a proxy server: `http://proxy.example.com:8080`. Scheme defaults to http, port defaults to 8080.
           auth: A niquests.auth.AuthBase or requests.auth.AuthBase object, may be passed instead of username/password.  username and password should be passed as arguments or in the URL
           timeout and ssl_verify_cert are passed to niquests.request.
           if auth_type is given, the auth-object will be auto-created. Auth_type can be ``bearer``, ``digest`` or ``basic``. Things are likely to work without ``auth_type`` set, but if nothing else the number of requests to the server will be reduced, and some servers may require this to squelch warnings of unexpected HTML delivered from the