test(proactive): the tips test runs skill-start as an interactive session

GitHub CI sets CI/GITHUB_ACTIONS, which gstack-session-kind reads as headless, and a headless start skips first-task detection, so the first-run tip never fires there (Free Tests shard 16 red at 0d7dbe6; green locally and on the Ubicloud pregate, which have no CI marker). The fixture now sets CLAUDE_CODE_ENTRYPOINT=cli, the positive interactive signal; reproduced locally with CI=1 and fixed.

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

test/proactive-skill-start.test.ts

@@ -54,6 +54,9 @@ function runStart(script: string, state: string, cwd = tmpHome): string {
     timeoutMs: 30_000,
     env: {
       PATH: process.env.PATH,
+      // An interactive session: CI sets CI/GITHUB_ACTIONS, which gstack-session-kind reads
+      // as headless, and headless skips first-task detection, so the tips never fire there.
+      CLAUDE_CODE_ENTRYPOINT: 'cli',
       HOME: tmpHome,
       GSTACK_HOME: state,
       GSTACK_STATE_DIR: state,