feat: generate package-manager-aware CI scripts

[huytdps13400]

Summary

• detect npm, Yarn, or Bun from the packageManager field or the corresponding lockfile
• prefer an explicit packageManager declaration and keep Yarn as the fallback
• render one executable reassure-tests.sh template with the selected install and Reassure commands
• document npm, Yarn, and Bun init workflows
• keep Jest as the test runner; this only changes package-manager commands

Verification

• yarn workspace @callstack/reassure-cli test --runInBand (10/10 passed)
• yarn validate
• yarn format:check
• yarn build
• git diff --check

Part of #452

[mdjastrzebski]

could we make this a template file, with some simple templating syntax for npm/yarn/bun install & npm/yarn/bun run .

It makes more sense then having separate copies of the file

[huytdps13400]

Implemented in 44fda7d. packages/cli/src/templates/reassure-tests is now the single template, and setUpCiScript() renders its install/run placeholders for npm, Yarn, or Bun after package-manager detection. The focused init suite covers all three outputs plus placeholder removal and executable mode.

[mdjastrzebski]

As far as I can tell this basically changes the template file to use bun instead of yarn. The run script is created from template but intended to be owned by the user, so they can already manually change the yarn installs => bun installs. If you want to continue working on it, then let's change scope so that changes in this PR would detect package manager, say npm/yarn/bun (pnpm might be more difficult due to need for hoisting which is not the default) and make reassure-tests.sh a template file that would be transformed when doing init to use. whatever Pkg Mgr user selected

[huytdps13400]

Thanks for clarifying the intended scope. I updated the PR in 44fda7d to detect npm, Yarn, and Bun from packageManager or lockfiles, then render a single reassure-tests.sh template with the matching commands. Explicit packageManager values take precedence and Yarn remains the fallback.

I also added coverage for all three declarations, npm/Yarn/Bun lockfiles, stale-lockfile precedence, executable mode, and complete placeholder rendering. yarn validate, yarn format:check, yarn build, and all 10 focused CLI tests pass.