feat: structured NFS options with auto-fsid and manual watched mounts

NFS exports: replace plain-text options string with typed booleans
(read_only, async, root_squash, subtree_check) + advanced JSON blob.
fsid is auto-generated via crypto/rand with collision retry and is
never user-settable. Breaking API change (options field removed).

Dashboard: filter disks to manual+samba+nfs sources only; no more
auto-discovery of all /proc/mounts entries.

Settings: new 'Puntos de montaje vigilados' card with add/remove
for manual mount points. AllowedRoots validation applied.

Version bump: 0.1.10 -> 0.2.0

web/src/pages/Dashboard.tsx

@@ -10,6 +10,10 @@ export default function Dashboard() {
     api.systemStatus().then(setStatus).catch(() => setStatus(null));
   }, []);
 
+  const visibleDisks = status?.disks.filter(
+    (d) => d.source === "manual" || d.source === "samba" || d.source === "nfs"
+  ) ?? [];
+
   return (
     <div className="space-y-6">
       <h1 className="text-2xl font-bold text-white">Dashboard</h1>
@@ -19,9 +23,9 @@ export default function Dashboard() {
           <h2 className="mb-4 text-sm font-semibold uppercase tracking-wide text-slate-400">
             Uso de disco
           </h2>
-          {status?.disks?.length ? (
+          {visibleDisks.length ? (
             <div className="space-y-4">
-              {status.disks.map((d) => (
+              {visibleDisks.map((d) => (
                 <div key={d.path}>
                   <div className="mb-1 flex justify-between text-sm">
                     <span className="text-slate-300">{d.path}</span>
@@ -39,7 +43,9 @@ export default function Dashboard() {
               ))}
             </div>
           ) : (
-            <p className="text-sm text-slate-500">Sin datos de disco.</p>
+            <p className="text-sm text-slate-500">
+              Sin puntos de montaje vigilados. Añádelos en Ajustes.
+            </p>
           )}
         </div>