fix: clone ca_manager Arc to unbreak master build

`crates/agent-tunnel/src/listener.rs:152-163` moves the same
`Arc<CaManager>` into both `AgentTunnelHandle` and `AgentTunnelListener`,
which fails to compile:

    error[E0382]: use of moved value: `ca_manager`
       --> crates/agent-tunnel/src/listener.rs:162:13

Clone the Arc for the handle so the move into `Self` still type-checks.

Root cause: PR #1773 added the `ca_manager` field to
`AgentTunnelListener`; PR #1775 used `ca_manager` in the same `bind()`
body for the handle initializer. Each PR's CI was green against its own
base, but the merge of #1775 on top of #1773 produced a semantic
conflict that wasn't textually conflicting, so GitHub merged it without
re-running CI.

This is the same fix originally proposed in #1790 (closed because #1781
incidentally carried it). Reapplied here because the revert removes
that incidental fix.

Author: irvingoujAtDevolution

crates/agent-tunnel/src/listener.rs

@@ -152,7 +152,7 @@ impl AgentTunnelListener {
         let handle = AgentTunnelHandle {
             registry: Arc::clone(&registry),
             agent_connections: Arc::clone(&agent_connections),
-            ca_manager,
+            ca_manager: Arc::clone(&ca_manager),
         };
 
         let listener = Self {