Duplicate entry: `content-analysis` and `content-analysis-plugin` are the same plugin (identical url + sha) — please remove the latter

## Summary

`marketplace.json` contains two entries for the same plugin — `content-analysis` (index 560) and `content-analysis-plugin` (index 561). They point at an identical `source.url` and `source.sha`. I'm the author of the plugin; please remove `content-analysis-plugin` and keep `content-analysis`.

## The two entries

```json
{
"name": "content-analysis",
"description": "Scientific content analysis for academic research. Supports the full workflow from research question to publication-ready output: codebook development, qualitative and quantitative coding, thematic analysis, and inter-coder reliability assessment. …",
"source": {
"source": "url",
"url": "https://github.com/PeterMalmkjaer/content-analysis-plugin.git",
"sha": "8427978e02fd3d3c904debac28a7d63bf449fdd8"
},
"homepage": "https://github.com/PeterMalmkjaer/content-analysis-plugin"
}
```

```json
{
"name": "content-analysis-plugin",
"description": "Scientific content analysis for academic research, built for Claude Cowork.",
"source": {
"source": "url",
"url": "https://github.com/PeterMalmkjaer/content-analysis-plugin.git",
"sha": "8427978e02fd3d3c904debac28a7d63bf449fdd8"
},
"homepage": "https://github.com/PeterMalmkjaer/content-analysis-plugin"
}
```

Same `url`, same `sha`, same `homepage`.

## Which one is correct

`content-analysis` is the canonical name. In the source repo, `.claude-plugin/plugin.json` declares:

```json
{ "name": "content-analysis", "version": "1.0.0", … }
```

`content-analysis-plugin` is the name of the **marketplace/repository**, declared in `.claude-plugin/marketplace.json` as the wrapper around the single plugin `content-analysis`. It looks like the marketplace name was ingested as a second plugin entry alongside the plugin it contains.

The duplicate also carries a stub description ("built for Claude Cowork") rather than the real one.

## Request

Remove the `content-analysis-plugin` entry; keep `content-analysis`.

I realise this may affect anyone who installed via `content-analysis-plugin@claude-community` — given the plugin's install numbers are very small, I'd rather have the catalogue correct. Happy to do it the other way round if you prefer to preserve that install path.

Submitted here rather than as a PR since external PRs are auto-closed and this is a catalogue correction rather than a new submission.