fix(plugins): publish the plugin SDK under the @getpaseo scope

The daemon imports the plugin SDK at runtime, but the workspace was named
@paseo/plugin and marked private, so it was never published. 0.5.0-beta.1
shipped @getpaseo/server depending on a package that does not exist and
`npm install @getpaseo/cli@beta` failed with a 404 for every user.

Two things hid it. sync-workspace-versions only rewrites deps matching
@getpaseo/*, so the "*" range on @paseo/plugin survived untouched into the
published tarball. And `npm pack --dry-run`, which is all release:check and
CI run, lists files without ever resolving the dependency graph.

Renaming to @getpaseo/plugin rather than publishing the old name: @paseo is
not our scope on npm, so that name could never have been published at all.
The rename also brings the package under the version-sync filter, which is
what pins it correctly from here on.

Plugins scaffolded against the old name still import @paseo/plugin. Both
spellings resolve through plugin-sdk-specifiers.ts, tagged COMPAT with a
removal date, so existing plugins keep loading.

This does not repair 0.5.0-beta.1 — a published tarball's dependencies
cannot be changed. The package publishes with the next release.

packages/server/package.json

@@ -74,12 +74,12 @@
     "@babel/parser": "^7.29.8",
     "@getpaseo/client": "0.5.0-beta.1",
     "@getpaseo/highlight": "0.5.0-beta.1",
+    "@getpaseo/plugin": "0.5.0-beta.1",
     "@getpaseo/protocol": "0.5.0-beta.1",
     "@getpaseo/relay": "0.5.0-beta.1",
     "@isaacs/ttlcache": "^2.1.4",
     "@modelcontextprotocol/sdk": "^1.20.1",
     "@opencode-ai/sdk": "1.14.46",
-    "@paseo/plugin": "*",
     "@xterm/headless": "^6.0.0",
     "ai": "5.0.78",
     "ajv": "^8.20.0",