feat(agent): surface the AI500 index board in chat, tools, and sidebar

- provider/nofxos: GetAI500ListCached — 5min TTL cache with stale
  fallback on upstream failure; ResolveClient routes through the claw402
  gateway when a wallet key is configured (user's claw402 model key ->
  CLAW402_WALLET_KEY env -> direct nofxos)
- new GET /api/ai500 endpoint serving the score-sorted board
- new get_ai500_list agent tool + prompt rule: when the user wants coin
  picks or creates a strategy without naming coins, consult AI500's
  high-scoring entries by default
- web: AI500 sidebar panel (rank, score badge, gain since entry,
  5min auto-refresh); clicking an entry asks the agent to analyze it

agent/tools.go

@@ -104,7 +104,7 @@ func plannerToolNamesForDomain(domain string) []string {
 		"get_strategies", "manage_strategy",
 		"manage_trader",
 		"get_balance", "get_positions", "get_trade_history",
-		"get_candidate_coins",
+		"get_candidate_coins", "get_ai500_list",
 		"get_watchlist", "manage_watchlist",
 		// Trade execution
 		"execute_trade",
@@ -115,7 +115,7 @@ func plannerToolNamesForDomain(domain string) []string {
 	case "__all__", "":
 		return all
 	case "market":
-		return []string{"get_market_snapshot", "get_market_price", "get_kline", "search_stock"}
+		return []string{"get_market_snapshot", "get_market_price", "get_kline", "search_stock", "get_ai500_list"}
 	case "account":
 		return []string{"get_balance", "get_positions", "get_trade_history", "get_exchange_configs"}
 	case "trader":
@@ -858,6 +858,22 @@ func buildAgentTools() []mcp.Tool {
 				},
 			},
 		},
+		{
+			Type: "function",
+			Function: mcp.FunctionDef{
+				Name:        "get_ai500_list",
+				Description: "Get the AI500 index board: crypto symbols scored 0-100 by AI with their gain since entering the index, sorted by score. Use this whenever the user asks what's in AI500, wants coin recommendations, or asks you to pick promising/strong coins and hasn't named specific ones — the top entries are the well-performing candidates.",
+				Parameters: map[string]any{
+					"type": "object",
+					"properties": map[string]any{
+						"limit": map[string]any{
+							"type":        "integer",
+							"description": "Max entries to return, default 20, max 100.",
+						},
+					},
+				},
+			},
+		},
 		{
 			Type: "function",
 			Function: mcp.FunctionDef{
@@ -934,6 +950,8 @@ func (a *Agent) handleToolCall(ctx context.Context, storeUserID string, userID i
 		return a.toolGetTradeHistory(tc.Function.Arguments)
 	case "get_candidate_coins":
 		return a.toolGetCandidateCoins(storeUserID, userID, tc.Function.Arguments)
+	case "get_ai500_list":
+		return a.toolGetAI500List(storeUserID, tc.Function.Arguments)
 	case "get_watchlist":
 		return a.toolGetWatchlist(lang)
 	case "manage_watchlist":