feat(report): add agent markdown export view

[quanru]

Summary

• Add a report-level Markdown View for agent analysis with syntax-highlighted markdown in the left sidebar and a screenshot timeline on the right.
• Add icon-only copy/download actions for report markdown and a ZIP containing report.md plus referenced screenshots.
• Include model and token usage context in markdown/HTML agent metadata, preserve file-backed screenshot refs, and keep markdown screenshot links aligned with exported image names.

Validation

• pnpm --dir apps/report test src/utils/markdown-export.test.ts
• pnpm --dir packages/core test tests/unit-test/report-markdown.test.ts tests/unit-test/html-utils.test.ts tests/unit-test/report-generator.test.ts tests/unit-test/report-cli.test.ts
• pnpm run lint
• pnpm exec nx build @midscene/report
• pnpm --dir apps/report generate-demo
• Browser DOM validation for Markdown View switching, icon-only download button, screenshot rendering, markdown image jump-to-screenshot behavior, and restored sidebar header layout

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: b22f4ad539

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[chatgpt-codex-connector]

Include every dump in report markdown export

When a report HTML contains multiple PlaywrightTasks groups, such as a merged Playwright report, dump is only the currently selected case from the store (initially the first case). The new Markdown View builds copy/download content from that single value, while the case selector is replaced by the markdown source in this mode, so exporting report.md silently omits all other cases in the same report. Build the markdown from dumps or preserve a way to select/aggregate cases in Markdown View.

Useful? React with 👍 / 👎.