fix(plugins): serverIsLive() falsely reported a server as running

resolveAllDashboardPorts() falls back to [DEFAULT_PORT] when the discovery
file has no live entry — a reasonable guess for the CLI/hook handler, but
wrong for the bootstrap's own liveness check: with no server running at all,
the bootstrap believed one was already up and never called startDashboard(),
confirmed against a real plugin install where the dashboard never started.
plugin-doctor.js's "Server" row had the same bug. Both now read the discovery
file directly and check PID liveness via the new liveServers() (livePids()
reused it instead of duplicating the read).

scripts/plugin-doctor.js

@@ -16,7 +16,6 @@ const path = require("path");
 const boot = require("./plugin-bootstrap");
 const { isOurEntry } = require("./install-hooks");
 const { getSettingsPath, getDataDir } = require("../server/lib/claude-home");
-const { resolveAllDashboardPorts } = require("../server/lib/server-info");
 const { mcpBuildStatus } = require("./check-mcp-build");
 
 const PLUGIN_ROOT = path.resolve(__dirname, "..");
@@ -63,18 +62,12 @@ function diagnose() {
     deps ? path.join(rt, "node_modules") : "missing — run /ccam-update"
   );
 
-  const ports = (() => {
-    try {
-      return resolveAllDashboardPorts();
-    } catch {
-      return [];
-    }
-  })();
+  const live = boot.liveServers();
   add(
-    ports.length ? "ok" : "fail",
+    live.length ? "ok" : "fail",
     "Server",
-    ports.length
-      ? `listening on ${ports.map((p) => `http://localhost:${p}`).join(", ")}`
+    live.length
+      ? `listening on ${live.map((s) => `http://localhost:${s.port}`).join(", ")}`
       : `not running — see ${path.join(rt, "server.log")}`
   );