obsidian-cli skill: add long-text limits and a direct-edit fallback

Problem

When an agent uses obsidian-cli to create, append, or otherwise edit a note with a long block of text, passing the full content through the CLI can trigger a JavaScript error. This makes long-note editing unreliable even though ordinary short inputs work.

Suggested guardrails for this skill

Please add guidance that limits the amount of text sent in one obsidian CLI invocation.

1. Prefer chunking long content into bounded pieces and write/apply the chunks sequentially when the operation supports it.
2. If safe chunking is not possible for a particular edit, fall back to the agent's built-in file/text editing tool to modify the Markdown file directly, rather than passing an oversized value to the CLI.
3. Document this fallback near the multiline-content examples so agents can apply it automatically.

This would prevent agents from repeatedly attempting an oversized CLI command and make long-text operations more robust.