fix(mcp): report HTTP listener recovery from its parsed failure

rea mcp --http printed "Choose another --port or stop the process using
it" for every listener failure except a missing host allowlist, so a host
lookup failure, an unassigned address or a permission denial got port
advice. StreamableHttpListenError already classifies the native failure
and owns a recovery for each kind.

Startup now always prints that owned recovery behind one shared lead-in,
and the fixed message is removed. The native cause text stays out of
stderr as before.

Fixes #7346

Co-Authored-By: gensokyo-dev <gensokyo-dev@users.noreply.github.com>
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/main/messages.ts

@@ -10,5 +10,6 @@ export const MCP_SHUTDOWN_FAILED =
   "REA could not close cleanly. End the REA process before starting it again.";
 export const SERVER_START_FAILED =
   "Do not repeat this startup. Tell the user REA could not start and ask them to restart the MCP client, then run `rea doctor`.";
-export const MCP_HTTP_LISTEN_FAILED =
-  "REA could not listen for MCP HTTP connections on the selected host and port. Choose another --port or stop the process using it.";
+/** The listener error owns recovery for its parsed failure; never its native cause text. */
+export const mcpHttpListenFailed = (remediation: string): string =>
+  `REA could not listen for MCP HTTP connections. ${remediation}`;

src/main/transport.ts

@@ -12,7 +12,7 @@ import type { OptionalProviderLoadResult } from "../application/OptionalObservat
 import { OwnedMcpServers } from "./OwnedMcpServers.js";
 import {
   MCP_CONNECTION_START_FAILED,
-  MCP_HTTP_LISTEN_FAILED,
+  mcpHttpListenFailed,
 } from "./messages.js";
 import { reportMcpTransportError } from "./reportMcpTransportError.js";
 
@@ -181,10 +181,7 @@ export const startMcpTransport = async (
     if (!cancelled) {
       const startFailure =
         cause instanceof StreamableHttpListenError
-          ? cause.classification.ok &&
-            cause.classification.value.kind === "host_allowlist"
-            ? cause.remediationAction
-            : MCP_HTTP_LISTEN_FAILED
+          ? mcpHttpListenFailed(cause.remediationAction)
           : MCP_CONNECTION_START_FAILED;
       serverLogger.error(
         {