Add remark ignore path settings

[astrobrownmusic]

Initial checklist

• I read the support docs
• I read the contributing guide
• I agree to follow the code of conduct
• I searched issues and discussions and could not find anything or linked relevant results below
• I made sure the docs are up to date
• I included tests (or that is not needed)

Description of changes

This wires the existing language-server ignore-path support into the VS Code extension by declaring remark.ignorePath and remark.ignorePathResolveFrom in the extension configuration, documenting both settings, and covering the custom ignore-path behavior in the formatter test.

unified-language-server already supports these settings on current main, and remark-language-server already documents them. This PR adds the VS Code extension side so users can configure the custom ignore path from settings.

After an initial macOS CI failure, I removed the client-side default for remark.ignorePathResolveFrom so the language server keeps ownership of its existing default behavior when users have not configured an ignore path.

The formatter test now calls VS Code's format-provider command directly and applies the returned edits. That verifies the language-server formatter without relying on platform-dependent UI formatter selection.

Verification:

• node -e "const assert=require('node:assert/strict'); const p=require('./package.json'); const props=p.contributes.configuration.properties; assert.equal(props['remark.ignorePath'].type,'string'); assert.deepEqual(props['remark.ignorePathResolveFrom'].enum,['dir','cwd']); assert.equal(Object.hasOwn(props['remark.ignorePathResolveFrom'],'default'),false); console.log('manifest settings ok')"
• npm.cmd run build
• git diff --check
• npm.cmd test in clean no-space worktree at C:\Users\t30br\.config\superpowers\worktrees\vscode-remark\ci-repro - 3 passing

npm.cmd test in my original Windows workspace could not produce a meaningful extension-host result because the path D:\Downloads\AI Makes me money autonomously was split by the runner as d:\Downloads\AI.

Closes #142

[remcohaszing]

This looks like AI slop. I’m sorry if you’re human.