feat(desktop): embed BoosAPI Desktop client as a subproject

Vendor the rebranded BoosAPI Desktop client (Tauri + Vue) into metapi as
a monorepo subdirectory under desktop/. Source only — node_modules,
dist, Cargo target and the upstream .git history are excluded.

desktop/ keeps its own independent Cargo workspace (desktop/src-tauri
with crates/*); it is not part of the backend boosapi crate, so a
`cargo check` at the metapi root still compiles only the backend. Build
the desktop app from desktop/src-tauri per desktop/README.md.

Note: app icons are still placeholder assets pending the final BoosAPI
logo. The updater signing keys live outside the repo and are not
included.

desktop/src-tauri/crates/open-agent-sdk/examples/08-oneshot-query.rs

@@ -0,0 +1,34 @@
+// Example 8: One-shot Query
+//
+// Quick one-shot agent query with restricted tools.
+//
+// Run: cargo run --example 08-oneshot-query
+
+use open_agent_sdk::{Agent, AgentOptions};
+
+#[tokio::main]
+async fn main() {
+    println!("--- Example 8: One-shot Query ---");
+
+    let mut agent = Agent::new(AgentOptions {
+        max_turns: Some(5),
+        allowed_tools: Some(vec!["Bash".to_string(), "Glob".to_string()]),
+        ..Default::default()
+    })
+    .await
+    .unwrap();
+
+    match agent.prompt("List the files in the current directory. Be brief.").await {
+        Ok(result) => {
+            println!("\n{}", result.text);
+            println!(
+                "\n({} turns, {} tokens)",
+                result.num_turns,
+                result.usage.input_tokens + result.usage.output_tokens
+            );
+        }
+        Err(e) => eprintln!("Error: {}", e),
+    }
+
+    agent.close().await;
+}