feat: remove obsolete CI workflows and update documentation for new CI structure

CONTRIBUTING.md

@@ -42,6 +42,18 @@ Shared code lives in `src/lib/`. **Do not** import `@lib/crypto` or `@lib/messag
 - **VS Code:** build then F5 or Install from VSIX (`packages/vscode`).
 - **CLI:** set `LEXAI_API_KEY`; never commit keys or put them in `~/.lexai/config.json`.
 
+## CI
+
+Gitea Actions runs one workflow per package (path-filtered):
+
+| Workflow | Package |
+| --- | --- |
+| `.gitea/workflows/ci-chrome.yml` | `packages/chrome` (+ `src/lib`, `tests`) |
+| `.gitea/workflows/ci-vscode.yml` | `packages/vscode` (+ `src/lib`) |
+| `.gitea/workflows/ci-cli.yml` | `packages/cli` (+ `src/lib`) |
+
+Deploy / preview / release workflows are not enabled yet.
+
 ## Pull request process
 
 1. Fork / branch from `main` (or `develop` if that is the active integration branch).