Homepage (TDD slice 2): the http probe method

Red test first: a raw TCP listener that never speaks HTTP must read down
under an http probe (up under tcp), while a real HTTP server reads up. This
test caught a real hang — the backgrounded listener inherited the test
runner's stdout pipe and held it open; fixed by redirecting its output and
killing both listeners in teardown.

scripts/homepage-status.py: probe() now dispatches on method. http does an
urlopen (any HTTP status = up; no connection = down); tcp connects.

The checker is now complete: tcp + http + wip + atomic write + generated_at.
Remaining slices: services.json schema, the pages + theme + toggle, the
Caddyfile (validate + two hashes), the git-driven deploy.

scripts/homepage-status.py

@@ -11,6 +11,8 @@ import os
 import socket
 import sys
 import tempfile
+import urllib.error
+import urllib.request
 from datetime import datetime, timezone
 
 TIMEOUT = 5  # seconds, per probe (Q11 / Q40)
@@ -18,6 +20,17 @@ TIMEOUT = 5  # seconds, per probe (Q11 / Q40)
 
 def probe(host, port, method="tcp"):
     """Return 'up' if the backend answers, else 'down'."""
+    if method == "http":
+        try:
+            urllib.request.urlopen(
+                urllib.request.Request("http://%s:%d/" % (host, port)),
+                timeout=TIMEOUT,
+            )
+            return "up"
+        except urllib.error.HTTPError:
+            return "up"  # an HTTP response of any status means the backend is up
+        except Exception:
+            return "down"
     try:
         with socket.create_connection((host, port), timeout=TIMEOUT):
             return "up"