feat: builder 简历生成 + 轻度优化 + 简历导入交付副本

自内部仓库剥离深度优化与 RAG 知识库后的交付版本：
- Builder 对话式简历生成（FSM + 意图路由 LLM 兜底增强）
- 条目级轻度优化：事实覆盖门禁 + STAR/bullet 修复链，功能/简介/成果与技术栈同级保护
- 简历导入：DOCX/PDF 解析、结构归一、手机号脱敏
- PostgreSQL 运行时 + Alembic 迁移链

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

backend/app/builder_conversation/expander_provider.py

@@ -0,0 +1,22 @@
+"""Lazy shared expander for card-driven rewrites that lack an agent reference.
+
+process_component_event is invoked by agent.py (over the 200-line edit limit, so its
+call signature is fixed) with no agent handle. Card actions that need a rewrite
+therefore share one process-wide expander built with the same factory as main.py.
+"""
+
+from __future__ import annotations
+
+from typing import Any
+
+_EXPANDER: Any = None
+
+
+def shared_expander() -> Any:
+    global _EXPANDER
+    if _EXPANDER is None:
+        from ..resume_expansion import build_expander
+        from ..settings import load_settings
+
+        _EXPANDER = build_expander(load_settings())
+    return _EXPANDER