feat: inject thread progress into agent prompt (#127)

Agents now receive a Thread Progress section showing current step number
and role visit count, eliminating tool calls to count turns.

- util-agent: new buildThreadProgress() helper
- agent-hermes: inject before continuation/first-visit prompt
- agent-claude-code: same injection point

Fixes #127

packages/agent-claude-code/src/claude-code.ts

@@ -7,6 +7,7 @@ import {
   type AgentRunResult,
   buildContinuationPrompt,
   buildRolePrompt,
+  buildThreadProgress,
   createAgent,
   getCachedSessionId,
   setCachedSessionId,
@@ -27,6 +28,10 @@ export function buildClaudeCodePrompt(ctx: AgentContext): string {
   if (ctx.outputFormatInstruction !== undefined && ctx.outputFormatInstruction !== "") {
     parts.push(ctx.outputFormatInstruction, "");
   }
+
+  // Inject thread progress so the agent knows step count and role visit count
+  parts.push(buildThreadProgress(ctx.steps, ctx.role), "");
+
   parts.push(rolePrompt, "", "## Task", ctx.start.prompt);
 
   if (!ctx.isFirstVisit) {