fix: remove sharp dependency that was never needed (#1141)

Sharp was an explicit dependency but nothing in the codebase imports it.
Chroma embeddings use ONNX Runtime via @chroma-core/default-embed, not sharp.
Sharp's native binary has a persistent Bun node_modules layout bug where
@img/sharp-libvips-* isn't placed alongside @img/sharp-darwin-* causing
ERR_DLOPEN_FAILED on every install.

- Remove sharp, @img/sharp-libvips-darwin-arm64, node-gyp from deps
- Remove node-addon-api from devDeps
- Remove @img cache clearing hacks from smart-install.js and sync-marketplace.cjs
- Replace with simple `bun pm cache rm` before install as general cache hygiene

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

package.json

@@ -118,7 +118,6 @@
     "@types/react": "^18.3.5",
     "@types/react-dom": "^18.3.0",
     "esbuild": "^0.27.2",
-    "node-addon-api": "^8.5.0",
     "np": "^11.0.2",
     "tsx": "^4.20.6",
     "typescript": "^5.3.0"