docs: add agent rules for dev server management and browser verification

- Section 6: Never start dev servers from the agent (prevents orphan
  processes and broken tmux panes)
- Section 7: Check tmux panes for compile errors (renumbered)
- Section 8: Verify compiled output in browser before committing
  (catches squint's silent empty-file failures)

dev/squint/src/dev/squint.cljs

@@ -33,6 +33,14 @@
     (js/requestAnimationFrame
       (fn [] (.removeAttribute el "data-no-transitions")))))
 
+(defn toggle-sidebar! [_e]
+  (when-let [layout (.querySelector js/document ".sidebar-layout")]
+    (.toggleAttribute layout "data-sidebar-open")))
+
+(defn close-sidebar! [_e]
+  (when-let [layout (.querySelector js/document ".sidebar-layout")]
+    (.removeAttribute layout "data-sidebar-open")))
+
 (defn section [title & children]
   [:section {:style {"margin-bottom" "2.5rem"}}
    [:h3 {:style {"color" "var(--fg-1)" "margin-bottom" "1rem"
@@ -404,8 +412,11 @@
   (let [active-page @!page]
     (sidebar/sidebar-layout {}
       (app-sidebar active-page)
+      (sidebar/sidebar-overlay {:on-click close-sidebar!})
       (sidebar/sidebar-layout-main {}
         [:div {:style {"padding" "2rem" "max-width" "960px"}}
+         [:div {:style {"display" "flex" "align-items" "center" "gap" "0.75rem" "margin-bottom" "1rem"}}
+          (sidebar/sidebar-mobile-toggle {:on-click toggle-sidebar!})]
          (case active-page
            "components" (components-page)
            "icons"      (icons-page)