fix: five from the full review

- doctor printed OPENAI_BASE_URL raw, the third place a credential-bearing URL
  reached the terminal; it goes through _endpoint like the others.
- dev.run left its output readers unjoined, so a child's last lines could be
  lost on exit. The threads are kept and joined during teardown.
- logs read each file and then reopened it to follow, so anything written in
  between appeared in neither. One handle now serves both.
- dev took --port straight from argparse: 0 would have served on an ephemeral
  port while printing 0, and oversized values reach socket.bind. It goes
  through _port_number first.
- doctor --redis-url overrode only the broker, so a stale result backend or
  cache was still pinged and the flag looked broken. All three endpoints now
  come from the URL given.

docsgpt/deploy/dev.py

@@ -181,6 +181,7 @@ def run(
     colour = out.isatty() if colour is None else colour
     lock = threading.Lock()
     running: list[tuple[Child, object]] = []
+    pumps: list[threading.Thread] = []
     try:
         for child in children:
             process = spawn(
@@ -195,7 +196,9 @@ def run(
                 start_new_session=os.name != "nt",
             )
             running.append((child, process))
-            threading.Thread(target=_pump, args=(child, process, out, lock, colour), daemon=True).start()
+            pump = threading.Thread(target=_pump, args=(child, process, out, lock, colour), daemon=True)
+            pump.start()
+            pumps.append(pump)
 
         while True:
             for child, process in running:
@@ -214,3 +217,7 @@ def run(
         return 0
     finally:
         _stop(running, grace, sleep)
+        # Join the readers: a child's last lines are still in flight when it exits, and dropping
+        # them loses exactly the output that says why it stopped.
+        for pump in pumps:
+            pump.join(timeout=grace)