add: marketplace entry with source "./" is rejected as unsupported "local" source

[sergical]

Summary

dotagents add fails for a repository whose marketplace entry uses "source": "./" (the plugin lives at the repository root). The error says the source type is unsupported, then says that only that same type is supported:

Plugin "agent-browser" not found in ~/.local/dotagents/vercel-labs/agent-browser. Matching marketplace entries use unsupported source types: local. Only local marketplace sources are supported.

Reproduce (dotagents 3.1.0, clean HOME)

export HOME=$(mktemp -d)
npx -y @sentry/dotagents init
npx -y @sentry/dotagents add vercel-labs/agent-browser --name agent-browser

--skill agent-browser and --ref <commit> give the same error.

The repository's .claude-plugin/marketplace.json:

"plugins": [
  { "name": "agent-browser", "source": "./", "strict": false,
    "skills": ["./skills/agent-browser"] }
]

Cause

In packages/dotagents/src/plugins/store.ts (still present on main at e42112b):

function localMarketplacePath(entry) {
  const { source } = entry;
  if (isString(source)) {return stripDotSlash(source);}   // "./" -> ""
  ...
}

discoverFromMarketplaces then checks if (!path). The empty string is falsy, so the entry goes to unsupportedSources, and marketplaceSourceType reports a string source as "local". "." works, because stripDotSlash(".") returns ".". Only "./" fails.

Expected

"./" resolves to the source root, the same as ".". A possible fix: return "." when stripDotSlash gives an empty string, or test path === null instead of !path. The same check applies to an object source with path: "./".

Workaround

A skill that agents.toml already declares still installs with dotagents install (the [[skills]] entry with path = "skills/agent-browser" does not go through plugin discovery). Only add fails.