fix(supervise): make the response poll idempotent and slow it to 250ms

The control-plane supervise poll archived the proposal on the same call
that returned the decision, so a dropped connection lost the operator's
decision (the retry saw `unknown`). Poll no longer archives — a re-poll
returns the same decision. Decided proposals still drop off the operator's
pending list (a response row exists); their rows are reaped when the
bottle is torn down or reconciled.

Also raise the grace-window poll interval from 50ms to 250ms now that each
poll is an HTTP round trip rather than a local file read.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

bot_bottle/supervise_server.py

@@ -82,7 +82,11 @@ ERR_INVALID_PARAMS = -32602
 ERR_INTERNAL = -32603
 
 DEFAULT_RESPONSE_TIMEOUT_SECONDS = 30.0
-MIN_RESPONSE_POLL_INTERVAL_SECONDS = 0.05
+# Grace-window poll cadence. 250 ms keeps the operator-visible latency low while
+# staying gentle on the shared control plane — each poll is now an HTTP round
+# trip, not a local file read, so the old 50 ms would be ~20 req/s per pending
+# proposal across every waiting agent (issue #469 review).
+MIN_RESPONSE_POLL_INTERVAL_SECONDS = 0.25
 
 # The per-host orchestrator control plane the shared supervise server attributes
 # each proposal to, by source IP. Mandatory — there is no single-tenant