feat(knowledge): 支持文件导入沉淀知识，知识图谱可视化随主题切换

- 后端新增 /api/knowledge/ingest/file：上传 md/txt/pdf/word/ppt/excel，
  转 Markdown 后走 wiki-capture LLM 蒸馏为陈述式知识笔记，失败回退逐字草稿
- service.capture_file + 文档专用蒸馏提示词，按主题拆分 1~4 页
- 知识图谱导出 HTML 支持 ?theme=light|dark，布局稳定后冻结，
  按度数缩放节点，悬停/点击聚焦邻居
- 前端知识库页新增「导入文件」对话框与 ingestKnowledgeFile API
- 智能体问答页与简介侧边栏 UI 优化；批量人物蒸馏脚本提取正文逻辑修正

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend-web/src/core/knowledge/api.ts

@@ -127,6 +127,30 @@ export async function ingestThreadsBatch(payload: BatchIngestPayload = {}) {
   );
 }
 
+export interface IngestFileResult {
+  note: KnowledgeNote;
+  created: boolean;
+  notes: KnowledgeNote[];
+  llm_fallback: boolean;
+}
+
+/** Import a file (md/txt/pdf/word/ppt/excel) into the KB as wiki note(s). */
+export async function ingestKnowledgeFile(
+  file: File,
+  opts: { title?: string; tags?: string; status?: string; model_name?: string | null } = {},
+) {
+  const form = new FormData();
+  form.append("file", file);
+  if (opts.title) form.append("title", opts.title);
+  if (opts.tags) form.append("tags", opts.tags);
+  if (opts.status) form.append("status", opts.status);
+  if (opts.model_name) form.append("model_name", opts.model_name);
+  // No Content-Type header — the browser sets the multipart boundary itself.
+  return parseResponse<IngestFileResult>(
+    await apiFetch(`${baseUrl()}/ingest/file`, { method: "POST", body: form }),
+  );
+}
+
 /** Resolve `[[wikilink]]` targets to note ids / vault pages. */
 export async function resolveWikilinks(targets: string[]) {
   const res = await parseResponse<{ resolved: WikilinkResolutionMap }>(

frontend-web/src/core/knowledge/hooks.ts

@@ -11,6 +11,7 @@ import {
   exportKnowledgeGraph,
   fetchVaultPage,
   getKnowledgeNote,
+  ingestKnowledgeFile,
   ingestThread,
   ingestThreadsBatch,
   listDuplicates,
@@ -106,6 +107,16 @@ export function useKnowledgeActions() {
       mutationFn: ingestThreadsBatch,
       onSuccess: invalidate,
     }),
+    ingestFile: useMutation({
+      mutationFn: ({
+        file,
+        opts,
+      }: {
+        file: File;
+        opts?: Parameters<typeof ingestKnowledgeFile>[1];
+      }) => ingestKnowledgeFile(file, opts),
+      onSuccess: invalidate,
+    }),
     exportGraph: useMutation({ mutationFn: exportKnowledgeGraph }),
     merge: useMutation({
       mutationFn: ({ primaryId, duplicateIds }: { primaryId: string; duplicateIds: string[] }) =>