Improve release process: consider nightly/automated releases #21

Summary

As more extensions migrate to @vscode/common-python-lsp, the current manual release process creates friction — consumer PRs must wait for a published version to pin against, and iterating on shared package changes requires local overrides or pre-release workarounds.

Problem

• Adding a new API to the shared package requires a full release before consumer extensions can reference it in CI.
• During active integration work across 5 extensions, version bumps and publishes become a bottleneck.
• No automated way to validate that a shared package change doesn't break any downstream consumer.

Possible Improvements

• Nightly / dev releases: Publish pre-release versions (e.g., 0.2.0-dev.20260427) on a schedule or on every merge to main, so consumers can opt into latest during development.
• CI-triggered publish: Automatically publish a stable release when a version bump is merged to main.
• Downstream integration tests: A workflow that installs the latest shared package into each consumer extension and runs their test suites.
• Changesets / release-please: Adopt a changelog-driven release tool to automate version bumps and release notes.