Inject fetch into REST transport

[Inv1x]

Summary

• Replace the REST transport's hard dependency on undici with a local fetch wrapper.
• Add support for injecting a custom fetch implementation when creating QdrantClient.
• Remove dispatcher-based Node-specific wiring and delegate transport behavior to the host runtime.
• Update documentation and unit coverage for the new fetch injection path.

Testing

• Added a unit test that verifies an injected fetch is used instead of global.fetch.
• Added a unit assertion that request init no longer includes dispatcher.

[Copilot]

Pull request overview

This PR removes the REST client’s hard dependency on undici/dispatcher wiring by introducing a local fetch-based transport and allowing callers to inject a custom fetch implementation via QdrantClient construction.

Changes:

• Remove undici + dispatcher-based RequestInit wiring and dependency entries.
• Add a new local fetcher abstraction and plumb fetch injection through QdrantClient → REST transport.
• Update docs and unit tests to cover fetch injection and ensure dispatcher is no longer set.

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
pnpm-lock.yaml	Removes top-level undici lock entries.
packages/js-client-rest/package.json	Drops undici dependency.
packages/js-client-rest/src/dispatcher.ts	Deletes Node-specific dispatcher implementation.
packages/js-client-rest/src/fetcher.ts	Adds new fetch wrapper used by REST transport (core behavioral change).
packages/js-client-rest/src/api-client.ts	Switches transport construction to the new fetcher + supports injected fetch.
packages/js-client-rest/src/types.ts	Adds fetch to internal REST args.
packages/js-client-rest/src/qdrant-client.ts	Exposes fetch injection on QdrantClientParams; deprecates maxConnections behavior.
packages/js-client-rest/tests/unit/api-client.test.ts	Adds assertions for no dispatcher and verifies injected fetch is used.
packages/js-client-rest/README.md	Updates support section and documents fetch injection.

Files not reviewed (1)

• pnpm-lock.yaml: Language not supported

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.