refactor(agent-loop): rename LoopAgent to ReactLoopAgent

Rename the concrete Agent class to make its ReAct-style reasoning loop
explicit in the name. Package name, default-export plugin (`AgentLoop`),
and the `ctx.agentLoop` service key are unchanged.

examples/coding-agent/tests/harness.ts

@@ -5,7 +5,7 @@ import type { SessionEvent } from '@deepseek-ai/dsh-session'
 import SystemPrompt from '@deepseek-ai/dsh-system-prompt'
 import ToolRegistry from '@deepseek-ai/dsh-tools'
 import AgentRegistry from '@deepseek-ai/dsh-agent'
-import AgentLoop, { LoopAgent } from '@deepseek-ai/dsh-agent-loop'
+import AgentLoop, { ReactLoopAgent } from '@deepseek-ai/dsh-agent-loop'
 import { LocalBashExecutor } from '@deepseek-ai/dsh-bash-local'
 import * as ToolBash from '@deepseek-ai/dsh-tool-bash'
 import * as LlmDeepSeek from '@deepseek-ai/dsh-llm-deepseek'
@@ -39,7 +39,7 @@ export async function codingHarness(workdir: string, persistenceRoot?: string):
   return ctx
 }
 
-export function waitForIdle(ctx: Context, agent: LoopAgent): Promise<void> {
+export function waitForIdle(ctx: Context, agent: ReactLoopAgent): Promise<void> {
   return new Promise((resolve) => {
     const dispose = ctx.on('agent/status', (subject, status) => {
       if (subject === agent && status === 'idle') {