feat: zero-friction side panel — auto-open on install, pill is clickable

Three changes to eliminate manual side panel setup:
- Auto-open side panel on extension install/update (onInstalled listener)
- gstack pill (bottom-right) is now clickable — opens the side panel
- Pill has pointer-events: auto so clicks always register (was: none)

User no longer needs to find the puzzle piece icon, pin the extension,
or know the side panel exists. It opens automatically on first launch
and can be re-opened by clicking the floating gstack pill.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

extension/background.js

@@ -172,6 +172,14 @@ chrome.runtime.onMessage.addListener((msg, sender, sendResponse) => {
     return true;
   }
 
+  // Open side panel from content script pill click
+  if (msg.type === 'openSidePanel') {
+    if (chrome.sidePanel?.open && sender.tab) {
+      chrome.sidePanel.open({ tabId: sender.tab.id }).catch(() => {});
+    }
+    return;
+  }
+
   // Sidebar → browse server command proxy
   if (msg.type === 'command') {
     executeCommand(msg.command, msg.args).then(result => sendResponse(result));
@@ -207,6 +215,19 @@ if (chrome.sidePanel && chrome.sidePanel.setPanelBehavior) {
   chrome.sidePanel.setPanelBehavior({ openPanelOnActionClick: true }).catch(() => {});
 }
 
+// Auto-open side panel on install/update — zero friction
+chrome.runtime.onInstalled.addListener(async () => {
+  // Small delay to let the browser window fully initialize
+  setTimeout(async () => {
+    try {
+      const [win] = await chrome.windows.getAll({ windowTypes: ['normal'] });
+      if (win && chrome.sidePanel?.open) {
+        await chrome.sidePanel.open({ windowId: win.id });
+      }
+    } catch {}
+  }, 1000);
+});
+
 // ─── Startup ────────────────────────────────────────────────────
 
 loadPort().then(() => {

extension/content.css

@@ -26,14 +26,14 @@
   font-size: 11px;
   font-weight: 500;
   letter-spacing: 0.02em;
-  pointer-events: none;
+  pointer-events: auto;
+  cursor: pointer;
   transition: opacity 0.5s ease;
   box-shadow: 0 2px 12px rgba(0, 0, 0, 0.4);
 }
 
 #gstack-status-pill:hover {
   opacity: 1 !important;
-  pointer-events: auto;
 }
 
 .gstack-pill-dot {

extension/content.js

@@ -19,6 +19,11 @@ function showStatusPill(connected, refs) {
   if (!statusPill) {
     statusPill = document.createElement('div');
     statusPill.id = 'gstack-status-pill';
+    statusPill.style.cursor = 'pointer';
+    statusPill.addEventListener('click', () => {
+      // Ask background to open the side panel
+      chrome.runtime.sendMessage({ type: 'openSidePanel' });
+    });
     document.body.appendChild(statusPill);
   }