feat: add agent tools and sanitize tool names for Anthropic API

Add 8 new agent-callable tools (sessions.list/history/create/delete,
agents.list, message.send, cron.list/trigger) and sanitize tool names
at the API boundary (dots → underscores) to comply with Anthropic's
`^[a-zA-Z0-9_-]{1,128}` requirement. Reverse-maps sanitized names
back to internal names for hook callbacks and tool execution.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/tools/executor.ts

@@ -22,7 +22,7 @@ export class ToolExecutor {
   }
 
   async execute(toolName: string, args: unknown, context?: ToolPolicyContext): Promise<ToolResult> {
-    const tool = this.registry.get(toolName);
+    const tool = this.registry.getByApiName(toolName);
     if (!tool) {
       return { success: false, output: '', error: `Tool '${toolName}' not found` };
     }