refactor: remove implicit content sniffing and table conversion

- Split loadCSV into parseCSVString (content) and loadCSVFromPath
  (path); drop isCSV/looksLikeCsv heuristics
- Delete coerceSparkTables and markedTable label-header magic;
  plain markdown tables now render as plain tables
- Add explicit markdown role=spark-table fence syntax that converts
  pipe tables to CSV at scan time, with dice-header validation
- Map ESM-only github-slugger and csv-parse browser build to CJS in
  jest config; add content-registry tests

src/markdown/index.ts

@@ -2,7 +2,6 @@ import { Marked, type MarkedExtension } from "marked";
 import { createDirectives, presetDirectiveConfigs } from "marked-directive";
 import markedAlert from "marked-alert";
 import markedMermaid from "./mermaid";
-import markedTable from "./table";
 import { gfmHeadingId } from "marked-gfm-heading-id";
 import markedColumns from "./columns";
 import markedCodeBlockYamlTag from "./code-block-yaml-tag";
@@ -14,7 +13,6 @@ const marked = new Marked()
   .use(gfmHeadingId())
   .use(markedAlert())
   .use(markedMermaid())
-  .use(markedTable())
   .use(markedCodeBlockYamlTag())
   .use(
     createDirectives([

src/markdown/table.ts

@@ -1,84 +0,0 @@
-import type { MarkedExtension, Tokens } from "marked";
-
-/**
- * 将表格数据转换为 CSV 格式字符串
- * @param headers 表头数组
- * @param rows 表格数据行
- * @returns CSV 格式字符串
- */
-function tableToCSV(headers: string[], rows: string[][]): string {
-  const escapeCell = (cell: string) => {
-    // 如果单元格包含逗号、换行或引号，需要转义
-    if (
-      cell.includes(",") ||
-      cell.includes("\n") ||
-      cell.includes('"') ||
-      cell.includes("#")
-    ) {
-      return `"${cell.replace(/"/g, '""')}"`;
-    }
-    return cell;
-  };
-
-  const headerLine = headers.map(escapeCell).join(",");
-  const dataLines = rows.map((row) => row.map(escapeCell).join(","));
-
-  return [headerLine, ...dataLines].join("\n");
-}
-
-export default function markedTable(): MarkedExtension {
-  return {
-    renderer: {
-      table(token: Tokens.Table) {
-        const header = token.header;
-        let roll = "";
-        let remix = "";
-
-        // Spark tables (dice-formula first column) are handled upstream by
-        // `coerceSparkTables` in the content registry — they're rewritten to
-        // `:md-table` directives before rendering. This renderer only handles
-        // label-based tables (md-table-label / md-roll-label / md-remix-label).
-        const labelIndex = header.findIndex((cell) => {
-          if (cell.text === "md-roll-label") {
-            roll = " roll=true";
-            return true;
-          } else if (cell.text === "md-remix-label") {
-            roll = " roll=true remix=true";
-            return true;
-          }
-          return cell.text === "md-table-label" || cell.text === "label";
-        });
-
-        // 默认表格渲染 - 使用 marked 默认行为
-        if (labelIndex === -1) return false;
-
-        const headers = token.header.map((cell) => cell.text);
-        headers[labelIndex] = "label";
-        const rows = token.rows.map((row) => row.map((cell) => cell.text));
-
-        if (header.findIndex((header) => header.text === "body") < 0) {
-          // 收集所有非 label 列的表头
-          const bodyColumns = headers.filter((cell) => cell !== "label");
-
-          // 构建 body 列的模板：**列名**：{{列名}}\n\n
-          const bodyTemplate = bodyColumns
-            .map((col) => `**${col}**：{{${col}}}`)
-            .join("\n\n");
-
-          headers.push("body");
-          rows.forEach((row) => {
-            row.push(bodyTemplate);
-          });
-        }
-
-        // 生成 CSV 数据
-        const csvData = tableToCSV(headers, rows);
-
-        // 渲染为 md-table 组件，内联 CSV 数据
-        // data-spark attribute is injected by the CLI directive scanner,
-        // not computed here.
-        return `<md-table ${roll}${remix}>${csvData}</md-table>\n`;
-      },
-    },
-  };
-}