Fix worker removal and improve web UI defaults

- Parse optional http:// scheme prefix on worker specs so a scheme-typed
  IP is stored cleanly and its remove button works.
- Delete workers by their stored DB host/port instead of re-parsing the
  rendered URL, and surface add/remove errors in the UI.
- Default new builds to git URL instead of zip upload.
- Show worker hostname/IP from agent status in the address column.
- Always include DB host/port in worker API output.

ctrl/workers.py

@@ -4,8 +4,16 @@ import requests
 
 
 def parse_worker(spec):
-    """'host:port' -> {'url': 'http://host:port', 'host': host, 'port': port}."""
-    host, _, port = spec.strip().rpartition(":")
+    """'host:port' -> {'url': 'http://host:port', 'host': host, 'port': port}.
+
+    Tolerates an optional http:// or https:// scheme prefix.
+    """
+    s = spec.strip()
+    for scheme in ("http://", "https://"):
+        if s.lower().startswith(scheme):
+            s = s[len(scheme):]
+            break
+    host, _, port = s.rpartition(":")
     if not host or not port.isdigit():
         raise ValueError(f"Invalid worker spec: {spec!r} (expected host:port)")
     return {"url": f"http://{host}:{port}", "host": host, "port": int(port)}
@@ -22,7 +30,7 @@ def configured_workers():
     return out
 
 
-def probe_worker(url, timeout=None):
+def probe_worker(url, host=None, port=None, timeout=None):
     """Return a normalized worker status dict, or None if unreachable."""
     timeout = timeout or settings.WORKER_STATUS_TIMEOUT
     try:
@@ -34,13 +42,17 @@ def probe_worker(url, timeout=None):
 
     info["url"] = url
     info["online"] = True
+    if host is not None:
+        info["host"] = host
+    if port is not None:
+        info["port"] = port
     return info
 
 
 def probe_all():
     workers = []
     for w in configured_workers():
-        status = probe_worker(w["url"])
+        status = probe_worker(w["url"], host=w["host"], port=w["port"])
         if status:
             workers.append(status)
         else: