feat(mcp): implement 4-pillar auto-sync, dynamic introspection, and non-blocking validation

- Pillar 1 (Runtime Auto-Sync):
  * Add sync_agent_tool_schemas() in src/mcp.rs to atomically export live tool schemas & instructions to ~/.gemini/antigravity/mcp/opencadstudio/
  * Automatically invoke sync on MCP startup (mcp::run()) and GUI automation startup (transport::listen())
  * Add --sync-mcp-schemas CLI flag in src/cli.rs and src/main.rs

- Pillar 2 (Development Hook):
  * Strengthen export_agent_tool_schemas test in src/mcp.rs to assert all schema files and instructions.md exist and are in sync on every cargo test run

- Pillar 3 (In-Band Dynamic Introspection):
  * Add 'tools' to READ_OPS in src/mcp.rs and query match in src/app/control/mod.rs
  * Enable agents to dynamically query live tool definitions and instructions via ocs_read (op: 'tools') over MCP or raw socket

- Pillar 4 (Non-Blocking Validation):
  * Set additionalProperties: true on ocs_capture schema in src/mcp.rs to prevent rigid schema rejection of emerging options

src/app/control/mod.rs

@@ -464,6 +464,7 @@ impl OpenCADStudio {
                 | "records"
                 | "record_schema"
                 | "capabilities"
+                | "tools"
                 | "entities"
                 | "layers"
                 | "header"
@@ -527,6 +528,17 @@ impl OpenCADStudio {
                 Task::none(),
             );
         }
+        if op == "tools" {
+            return (
+                json!({
+                    "ok": true,
+                    "status": "completed",
+                    "tools": crate::mcp::tool_definitions(),
+                    "instructions": crate::mcp::INSTRUCTIONS
+                }),
+                Task::none(),
+            );
+        }
         if op == "commands" {
             let mut names = crate::command::all_registered_command_names();
             let mut names: Vec<String> = names.drain(..).map(str::to_owned).collect();

src/app/control/transport.rs

@@ -53,6 +53,7 @@ fn listen(sender: mpsc::Sender<Envelope>) -> std::io::Result<()> {
     let mut file = options.open(&path)?;
     write!(file, "{descriptor}")?;
     drop(file);
+    let _ = crate::mcp::sync_agent_tool_schemas();
     let clients = Arc::new(AtomicUsize::new(0));
     for stream in listener.incoming().flatten() {
         if clients.fetch_add(1, Ordering::SeqCst) >= 8 {