refactor: remove BlockRun provider, retain Claw402 as sole x402 payment provider

Remove all BlockRun (Base + Solana wallet) references from codebase:
- Delete blockrun_base.go, blockrun_sol.go, wallet setup docs, icon
- Move shared EIP-712 signing code to x402.go for Claw402 reuse
- Clean up provider constants, model lists, UI components, translations
- Update all README files (EN + 6 i18n) and getting-started docs

mcp/client.go

@@ -44,7 +44,7 @@ var (
 
 // TokenUsage represents token usage from AI API response
 type TokenUsage struct {
-	Provider         string // payment channel: "claw402", "blockrun-base", "blockrun-sol", or native provider name
+	Provider         string // payment channel: "claw402" or native provider name
 	Model            string
 	PromptTokens     int
 	CompletionTokens int
@@ -52,13 +52,11 @@ type TokenUsage struct {
 }
 
 // Channel returns the payment channel category for telemetry.
-// Returns "claw402", "blockrun", or "native" based on the provider.
+// Returns "claw402" or "native" based on the provider.
 func (u TokenUsage) Channel() string {
 	switch u.Provider {
 	case ProviderClaw402:
 		return "claw402"
-	case ProviderBlockRunBase, ProviderBlockRunSol:
-		return "blockrun"
 	default:
 		return "native"
 	}