Always clean stale taps before creating new ones

deleteTap before createTap in all four call sites:
snapshot restore, cold boot, agent start, snapshot create.
Prevents "Device or resource busy" from leftover taps.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/agent-manager.ts

@@ -268,6 +268,7 @@ export async function startAgent(
   // Setup network
   ensureBridge();
   ensureNat();
+  deleteTap(tapDevice); // clean stale tap from previous run
   createTap(tapDevice);
 
   // Boot VM

src/snapshot.ts

@@ -63,6 +63,7 @@ export async function createSnapshot() {
   log("Setting up network...");
   ensureBridge();
   ensureNat();
+  deleteTap(snap.tapDevice); // clean stale tap from previous run
   createTap(snap.tapDevice);
 
   let proc: ChildProcess | null = null;

src/vm.ts

@@ -78,6 +78,7 @@ export class VMInstance {
       log(verbose, `VM ${id}: restoring from snapshot...`);
       ensureBridge();
       ensureNat();
+      deleteTap(snap.tapDevice); // clean stale tap from previous run
       createTap(snap.tapDevice);
 
       // Spawn firecracker and load snapshot
@@ -155,6 +156,7 @@ export class VMInstance {
       log(verbose, `VM ${id}: creating tap ${tapDevice}...`);
       ensureBridge();
       ensureNat();
+      deleteTap(tapDevice); // clean stale tap from previous run
       createTap(tapDevice);
 
       log(verbose, `VM ${id}: booting...`);