ci: remove duplicate Code Quality workflow

[HermesYP]

Removes .github/workflows/ci.yml, now redundant after #1 split it into two dedicated workflows.

Why

ci.yml ("Code Quality") defines the same two jobs as the workflows added in #1. With both present, every pull request runs three workflows and reports four status checks, with duplicate names:

Workflow	Job name
ci.yml	Frontend
ci.yml	Native
frontend-quality.yml	Frontend
native-quality.yml	Native

The duplicate Frontend / Native names make it ambiguous which check branch protection would bind to, and each PR burns a redundant frontend run plus a redundant seven-minute native run.

What remains afterwards

Workflow	Job name	Trigger
frontend-quality.yml	Frontend	pull_request
native-quality.yml	Native	pull_request

The libasound2-dev, libgtk-3-dev, libmpv-dev, and related Linux build dependencies are not lost — they are defined in full in native-quality.yml. No behavior from ci.yml is dropped; both job definitions were carried over verbatim in #1.

Tradeoff

ci.yml is shared with upstream harborstremio/harbor. Deleting it in this fork means future git merge upstream/main runs that touch that file will conflict. That is the cost of having exactly two checks instead of four, and it is the intended direction for this fork.