docs: update PRD with comprehensive extension features and UX integration strategy

- Added UX strategy: Extension for Quick Actions, Frontend for Management
- Organized features into 4 phases (Phase 1 completed)
- Added 14 new extension features (FR-EXT-07 to FR-EXT-17):
  * Smart Monitoring: Price alerts, whale tracking, rug pull detection
  * Trading Intelligence: Token analysis, entry/exit suggestions, portfolio tracker
  * Content Creation: Chart screenshots, AI thread generator
  * Productivity: Quick actions, notifications, keyboard shortcuts
- Added Feature Responsibility Matrix showing Extension vs Frontend roles
- Added Settings Sync strategy (FR-EXT-06) with deep links to frontend
- Documented state sync architecture: Extension ↔ Backend API ↔ Frontend

surfsense_browser_extension/sidepanel/context/PageContextProvider.tsx

@@ -0,0 +1,72 @@
+import { createContext, useContext, useEffect, useState, type ReactNode } from "react";
+
+/**
+ * Page context types
+ */
+export type PageType = "dexscreener" | "coingecko" | "twitter" | "generic";
+
+export interface TokenData {
+    chain: string;
+    pairAddress: string;
+    tokenSymbol?: string;
+    price?: string;
+    volume24h?: string;
+    liquidity?: string;
+}
+
+export interface PageContext {
+    url: string;
+    title: string;
+    pageType: PageType;
+    tokenData?: TokenData;
+}
+
+interface PageContextValue {
+    context: PageContext | null;
+    updateContext: (context: PageContext) => void;
+}
+
+const PageContextContext = createContext<PageContextValue>({
+    context: null,
+    updateContext: () => { },
+});
+
+export function usePageContext() {
+    return useContext(PageContextContext);
+}
+
+/**
+ * Provider for page context detection
+ * Listens to messages from content scripts
+ */
+export function PageContextProvider({ children }: { children: ReactNode }) {
+    const [context, setContext] = useState<PageContext | null>(null);
+
+    useEffect(() => {
+        // Listen for page context updates from content script
+        const handleMessage = (message: any) => {
+            if (message.type === "PAGE_CONTEXT_UPDATE") {
+                setContext(message.data);
+            }
+        };
+
+        chrome.runtime.onMessage.addListener(handleMessage);
+
+        // Request initial context
+        chrome.tabs.query({ active: true, currentWindow: true }, (tabs) => {
+            if (tabs[0]?.id) {
+                chrome.tabs.sendMessage(tabs[0].id, { type: "GET_PAGE_CONTEXT" });
+            }
+        });
+
+        return () => {
+            chrome.runtime.onMessage.removeListener(handleMessage);
+        };
+    }, []);
+
+    return (
+        <PageContextContext.Provider value={{ context, updateContext: setContext }}>
+            {children}
+        </PageContextContext.Provider>
+    );
+}