feat: add --no-workspace-macros opt-out for workspace macro loading

Mirrors --no-workspace-mcp exactly: a CLI-only flag backed by an
AppConfig field (default false) that disables .coyote/macros in both
the resolved macro policy and Macro::load's workspace-then-global
preference, so the two always agree (custom-commands design §5).

src/config/request_context.rs

@@ -2505,7 +2505,7 @@ impl RequestContext {
             self.agent.as_ref(),
             self.session.as_ref(),
             &crate::repl::builtin_command_names(),
-            false,
+            self.app.config.no_workspace_macros,
         )
     }