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/skill_groups.py

@@ -0,0 +1,22 @@
+"""Skill group updates that preserve recommender-assigned categories.
+
+apply_update_skill_groups lives in an over-limit module and keeps keyword-only
+classification for manual patch edits; this wrapper reuses its cleaning and then
+re-groups with the recommender's (LLM) categories, which win over keywords.
+"""
+
+from __future__ import annotations
+
+from typing import Any
+
+from .resume_document_mutations import apply_update_skill_groups
+from .skill_classifier import classify_skills
+
+
+def update_skill_groups(
+    content: dict[str, Any], skills: list[Any], preferred_categories: dict[str, str] | None = None
+) -> dict[str, Any]:
+    result = apply_update_skill_groups(content, skills)
+    flat = [skill for group in result.get("skill_groups") or [] for skill in group.get("skills") or []]
+    result["skill_groups"] = classify_skills(flat, preferred=preferred_categories)
+    return result