chore: add sproutclaw git workflow and track local extensions

Document main/upstream-sync/feature branch strategy, add sync/push
scripts, track .pi/agent extensions and webui in git, and disable
startup changelog via showChangelogOnStartup.

Co-authored-by: Cursor <cursoragent@cursor.com>

.pi/agent/extensions/webui/frontend/src/components/pwa/PwaUpdatePrompt.module.css

@@ -0,0 +1,74 @@
+.bar {
+  position: fixed;
+  left: 50%;
+  bottom: calc(16px + env(safe-area-inset-bottom));
+  transform: translateX(-50%);
+  z-index: 9999;
+  display: flex;
+  align-items: center;
+  gap: 12px;
+  max-width: min(92vw, 420px);
+  padding: 12px 14px;
+  border-radius: 14px;
+  background: rgba(255, 255, 255, 0.96);
+  border: 1px solid #e5e7eb;
+  box-shadow: 0 10px 30px rgba(15, 23, 42, 0.12);
+  backdrop-filter: blur(10px);
+}
+
+.text {
+  flex: 1;
+  min-width: 0;
+  font-size: 13px;
+  line-height: 1.4;
+  color: #374151;
+}
+
+.actions {
+  display: flex;
+  gap: 8px;
+  flex-shrink: 0;
+}
+
+.primary,
+.secondary {
+  height: 32px;
+  padding: 0 12px;
+  border-radius: 8px;
+  font-size: 12px;
+  font-weight: 500;
+  cursor: pointer;
+  border: 1px solid transparent;
+}
+
+.primary {
+  color: #fff;
+  background: #2563eb;
+  border-color: #2563eb;
+}
+
+.primary:hover {
+  background: #1d4ed8;
+}
+
+.secondary {
+  color: #4b5563;
+  background: #fff;
+  border-color: #d1d5db;
+}
+
+.secondary:hover {
+  background: #f3f4f6;
+}
+
+@media (max-width: 480px) {
+  .bar {
+    flex-direction: column;
+    align-items: stretch;
+    gap: 10px;
+  }
+
+  .actions {
+    justify-content: flex-end;
+  }
+}