chore: 清理 docs 目录冗余文档（55个→9个）

删除:
- docs/1.0/ 全部22个（旧Simple KB文档，已被替代）
- docs/2.0/ 全部2个（空文件/过时）
- docs/design/ 全部4个（旧功能设计）
- docs/plans/ 旧版5个（保留v2.0设计文档）
- docs/superpowers/ 全部4个（飞书集成文档）
- docs/根目录杂项 8个（开发规范/快速参考/调试/飞书/Git设置）
- docs/3.0/knowledge_graph_analysis.md（不相关）

保留:
- docs/3.0/ 考核工作流设计 2个
- docs/plans/ v2.0设计文档 1个
- docs/tests/ 测试文档 6个
合计: 55个 → 9个

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/design/feat-auto-title-generation.md

@@ -1,68 +0,0 @@
-# Feature Design: Automatic Title Generation (feat-auto-title-generation)
-
-## 1. Overview
-This feature automatically generates meaningful titles for uploaded documents and chat sessions using AI. It aims to replace generic filenames and "New Conversation" labels with content-aware titles, improving user experience and organization.
-
-## 2. Requirements
-
-### 2.1 Document Title Generation
-- **Trigger**: Automatically triggered after text extraction (Fast or Precise mode).
-- **Process**:
-    1. Extract a sample of the document content (first 2,000 - 3,000 characters).
-    2. Send the content to the default LLM with a specific generation prompt.
-    3. Update the `KnowledgeBase` record with the generated title.
-- **Rules**:
-    - The title should be concise (less than 50 characters).
-    - It should be in the user's preferred language (defaulting to the detected document language if possible).
-    - Output should be "raw" (no preamble like "The title is...").
-
-### 2.2 Chat Title Generation
-- **Trigger**: Triggered after the first user message and its corresponding assistant response are recorded.
-- **Process**:
-    1. Collect the initial message pair.
-    2. Send the pair to the default LLM with a generation prompt.
-    3. Update the `SearchHistory` record's `title` field.
-- **Rules**: Same as document titles.
-
-## 3. Technical Design
-
-### 3.1 Data Model Changes
-- **KnowledgeBase Entity**: Add a `title` field (nullable, optional). If empty, fallback to `originalName`.
-- **SearchHistory Entity**: No changes required (has `title`).
-
-### 3.2 Backend Implementation
-
-#### KnowledgeBaseService
-- Add `generateTitle(kbId: string)` method.
-- Hook into `processFile` after `updateStatus(kbId, FileStatus.EXTRACTED)`.
-
-#### ChatService / SearchHistoryService
-- Add logic to check if the session title is still the default (usually the first message snippet) and trigger `generateTitle(historyId: string)` after the first assistant response.
-
-#### Prompt Design
-- **Document Prompt**:
-  ```text
-  You are a document analyzer. Read the provided text and generate a concise, professional title (max 50 chars). 
-  Return ONLY the title.
-  Language: {userLanguage}
-  Text: {contentSample}
-  ```
-- **Chat Prompt**:
-  ```text
-  Based on the following conversation snippet, generate a short, descriptive title (max 50 chars) that summarizes the topic.
-  Return ONLY the title.
-  Language: {userLanguage}
-  Snippet:
-  User: {userMessage}
-  AI: {aiResponse}
-  ```
-
-## 4. Verification Plan
-
-### Automated Tests
-- Integration tests in `KnowledgeBaseService` to verify the title field is updated after processing.
-- Mock LLM responses to ensure the title update logic works.
-
-### Manual Verification
-- Upload various files (PDF, Word, TXT) and verify the displayed title in the knowledge base list.
-- Start a new chat, send a message, and check the sidebar for the updated session title.