feat: v3 robustness upgrade — EasyOCR, failure recovery, minimum content check

- OCR: EasyOCR (primary, ch_sim+en) with PaddleOCR fallback for Windows compatibility
- Validation: _check_minimum_content() rejects empty-shell JRXML (no band/textField)
- Retry: MAX_RETRY 3→5, exhaustion records pending_failure_context for next-turn auto-injection
- Finalize: only saves jrxml_versions on pass, preserves last good final_jrxml on fail
- Extract JRXML: improved empty markdown block handling and XML fragment fallback
- UI: real-time node progress via placeholder updates, initial "analyzing" feedback
- UI: use agent_state (full) instead of node_state (partial) for summary card routing
- UI: unknown template_type now gives LLM meaningful image context instead of metadata
- Docs: updated CLAUDE.md and CODE_GUIDE.md to reflect all v3 changes

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

agent/state.py

@@ -37,3 +37,6 @@ class AgentState(TypedDict, total=False):
 
     # 需求5：错误自增长（记录修正前的状态，供 validate 节点判断是否入知识库）
     last_error_case: dict
+
+    # 需求6：失败上下文传递 — 重试耗尽后暂存失败信息，下次用户输入时自动注入
+    pending_failure_context: dict