refactor: replace any types with proper TypeScript types across gateway client, hooks, and components

- Add GatewayMessage and JsonPayload interfaces to gateway.ts
- Type WebSocket message parsing with GatewayMessage instead of any
- Use ReturnType<typeof setTimeout> for timer refs
- Type chat event payload destructuring explicitly
- Add ChatPayloadMessage interface for extractText()
- Replace any casts in loadSessions/loadHistory with typed assertions
- Add str() helper in ToolCall.tsx for safe unknown→string extraction
- Use Extract<MessageBlock, ...> type guards instead of `as any` casts
- Type CodeBlock children prop properly

src/types/index.ts

@@ -11,7 +11,7 @@ export interface ChatMessage {
 export type MessageBlock =
   | { type: 'text'; text: string }
   | { type: 'thinking'; text: string }
-  | { type: 'tool_use'; name: string; input: any; id?: string }
+  | { type: 'tool_use'; name: string; input: Record<string, unknown>; id?: string }
   | { type: 'tool_result'; content: string; toolUseId?: string; name?: string }
   | { type: 'image'; mediaType: string; data?: string; url?: string };