feat(rag): harden post-LightRAG runtime

Retire legacy OCR/media/evidence fallbacks, add local-folder event bus and Page Aggregate guards, and archive completed design checklists.

Validation: cargo test -p mnote-web -- --test-threads=1; cargo test --workspace -- --test-threads=1; git diff --check; codegraph sync .; codegraph_status.

scripts/task530-knowledge-rag-page-ai-final-answer-smoke.js

@@ -177,8 +177,8 @@ async function main() {
       .count();
     const prompt = [
       "请调用 mnote_knowledge_rag_query 检索资料库。",
-      "问题：scan image start 这份扫描 PDF 里出现了什么关键短语？",
-      "最终只输出一句中文结论，必须包含返回的 citationMarkdown 链接，不要描述检索过程，不要输出 raw JSON，不要编造页码。",
+      "问题：这个图片资料在资料库里是什么内容？调用工具时请把 sourcePaths 参数设为 [\"新页面233155/image copy 6.png\"]。",
+      "最终只输出一句中文结论，必须包含返回的 citationMarkdown 链接；如果 locatorDegraded=true，必须说明来源定位降级，不要描述检索过程，不要输出 raw JSON，不要编造页码或 bbox。",
     ].join("\n");
     await page.locator("[data-page-ai-input]").fill(prompt, { timeout: UI_TIMEOUT_MS });
     await page.locator('[data-page-ai-action="send"]').click({ timeout: UI_TIMEOUT_MS });
@@ -194,7 +194,7 @@ async function main() {
         );
         const node = nodes.slice(countBefore).at(-1) || nodes.at(-1);
         const text = node?.querySelector(".wolai-page-ai-message-text")?.textContent || "";
-        return text.includes("first image in PDF") && text.includes("scan-image-start.pdf") && text.includes("p.1");
+        return text.includes("来源定位降级") && text.includes("image copy 6.png");
       },
       assistantCount,
       { timeout: Math.max(UI_TIMEOUT_MS, 180_000) },
@@ -202,11 +202,12 @@ async function main() {
 
     const assistantText = await newestAssistantText(page, assistantCount);
     const assistantLinks = await newestAssistantLinks(page, assistantCount);
-    assert(assistantText.includes("first image in PDF"), `可见回答缺少关键短语: ${assistantText}`);
-    assert(assistantText.includes("scan-image-start.pdf"), `可见回答缺少来源文件名: ${assistantText}`);
-    assert(assistantText.includes("p.1"), `可见回答缺少页码 citation 文本: ${assistantText}`);
+    assert(assistantText.includes("image copy 6.png"), `可见回答缺少当前资料来源文件名: ${assistantText}`);
+    assert(assistantText.includes("来源定位降级"), `可见回答缺少 degraded citation 口径: ${assistantText}`);
+    assert(!/\bp\.\d+\b/i.test(assistantText), `degraded citation 不应编造页码: ${assistantText}`);
+    assert(!/bbox/i.test(assistantText), `degraded citation 不应编造 bbox: ${assistantText}`);
     assert(
-      assistantLinks.some((link) => link.text.includes("scan-image-start.pdf") && link.href.includes("resourceTab=")),
+      assistantLinks.some((link) => link.text.includes("来源定位降级") && link.href.includes("resourceTab=")),
       `可见回答缺少可点击 resourceTab citation: ${JSON.stringify(assistantLinks)}`,
     );
     assert(!assistantText.includes("citationMarkdown"), `可见回答泄漏工具字段名: ${assistantText}`);