chore: scaffold vue

[joker23]

Note

Low Risk
Scaffolding and CI/release config only; no runtime SDK behavior and automated npm release for Vue remains disabled.

Overview
Adds a new packages/sdk/vue workspace for @launchdarkly/vue-client-sdk (0.1.0) as an experimental Vue 3 client SDK shell—build/lint/test tooling, README with a production caution, and a placeholder src/index.ts (full implementation deferred).

Monorepo wiring includes the yarn workspace, root tsconfig project reference, release-please manifest/config, and a vue.yml CI job via shared ./actions/ci. release-please also gains manual publish and a release-vue job that depends on release-browser but stays disabled (if: false) until the package is ready to ship.

^{Reviewed by Cursor Bugbot for commit f574d76. Bugbot is set up for automated code reviews on this repo. Configure here.}

[github-actions]

@launchdarkly/js-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 26365 bytes
Compressed size limit: 29000
Uncompressed size: 129044 bytes

[github-actions]

@launchdarkly/js-client-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 38739 bytes
Compressed size limit: 39000
Uncompressed size: 212244 bytes

[github-actions]

@launchdarkly/browser size report
This is the brotli compressed size of the ESM build.
Compressed size: 179654 bytes
Compressed size limit: 200000
Uncompressed size: 831422 bytes

[github-actions]

@launchdarkly/js-client-sdk size report
This is the brotli compressed size of the ESM build.
Compressed size: 31979 bytes
Compressed size limit: 34000
Uncompressed size: 114243 bytes