🐛 Omit local images from document exports

[baealex]

🎯 Goal

• Prevent document-only Markdown exports and copied Markdown from exposing local image asset paths.
• Remove noisy omitted-image comments from document-only exports.

🛠️ Core Changes

• Omit local /assets/images/ Markdown images from document-only Markdown output.
• Omit local image tags from document-only HTML output without inserting comments.
• Apply the same local image filtering to the Copy Markdown action.
• Harden Markdown image scanning for nested brackets, parenthesized URLs, angle URLs, and optional titles.

🧠 Key Decisions

• Keep external images and external URLs unchanged.
• Keep ZIP exports as the path for preserving local image assets.
• Avoid exposing internal local asset paths when assets are not bundled.

🧪 Verification Guide

How to verify

1. Run pnpm --filter @ocean-brain/client test -- note-export.spec.ts --run.
2. Run pnpm --filter @ocean-brain/client lint.
3. Run pnpm --filter @ocean-brain/client type-check.

Expected result

• Document-only Markdown/HTML exports omit local images and local asset paths.
• External images remain in the exported document.
• All commands pass.

✅ Checklist

• Lint completed
• Type-check completed
• Tests completed
• Documentation updated (if needed)